What if, in D&D Next, every 2e Sphere and 3e Domain, and every Portfolio were to become a distinct generic Deity in D&D Next? The 5e PHB would offer a selection of, say, twelve of these Deities. An iconic nickname (itself gleaned from D&D lore) might be offered as a “fluff handle” for homebrew campaigns.
I suggest reverse engineering the generic D&D Next Deities. Take all the core 2e priest spheres, the core 3e Greyhawkish gods and domains, the core 4e Nerath gods, the Asgardian, Pharaonic, and Olympian pantheons, plus any other iconic D&D gods (for example, Mishakal from Dragonlance and the famous gods from Forgotten Realms—and even have a look at Mystara, Eberron, and Dark Sun), and distill them into a generic array of spheres/domains. Also, look at their Portfolios in their official descriptions—there are many more Portfolios than there are Cleric Domains. But in D&D Next, each sphere/domain/portfolio is called a "Deity".
Here's a list of the core 3.5e Cleric Domains as they might appear as distinct 5e Deities. The choice of particular nicknames is somewhat arbitrary. Any evocative nickname from any D&D deity from any campaign setting would be fitting. The use of a particular nickname doesn't mean that the generic Deity is actually like that campaign setting's Deity:
The God of Air ("The Far Reacher", a genericized nickname of Phaulkon from Greyhawk)
The God of Animals/Beasts (“The Wild One”, a genericized nickname of Chislev from Dragonlance)
The God of Chaos
The God of Death (“The Reaper”, a genericized nickname of Nerull)
The God of Destruction
The God of Stone [changed from “Earth”, so as to not mean “planet Earth”] ("The Unyielding Rock", a genericized nickname of Fortubo from Greyhawk]
The God of Evil (“The Dark God”, a genericized nickname of Tharizdun)
The God of Fire
The God of Goodness
The God of Healing (“The Healing Hand”, a genericized nickname of Mishakal from Dragonlance)
The God of Knowledge
The God of Law
The God of Luck (“Lady Luck”/”Lord Luck”, a genericized nickname of Avandra from Nerath)
The God of Plants
The God of Magic (“The Archmage”, a genericized nickname of Boccob from Greyhawk)
The God of Protection (“The Invincible”, a genericized nickname of Heironeous from Greyhawk)
The God of Strength (“The Brawler”, a genericized nickname of Kord from Greyhawk)
The God of the Sun (“The Shining One”, a genericized nickname of Pelor from Greyhawk)
The God of Travellers (“The Dweller on the Horizon”, a genericized nickname of Fharlanghn from Greyhawk)
The God of Trickery (“The Laughing Rogue”, a genericized nickname of Olidamarra from Greyhawk)
The God of War
The God of Water ("The Vault of the Oceans", a genericized nickname of Xerbo from Greyhawk)
In this way, not so much has to be packed into a single Deity, with the fluff kept to a minimum. Every bit of fluff makes D&D Next more vulnerable to forming yet another default setting, with just a more genericized Nerath-like pantheon.
The core names might be gender-free, so that each icon could be either male or female. The term “god” in intended as a genderless word which includes “goddess”, in the same way that “actor” is replacing the word “actress”. “God” also includes a philosophy, for example, “The Way of the Sun” as a philosophy.
In various campaign settings, a single God will have the Portfolio of multiple PHB gods. For example, in an Olympian setting, Apollo is both the "God of Light" and the "God of Music".
Enough "Deities" (that is, Portfolios masquerading as generic Deities) ought to be included in the PHB to recreate the core 3.5e Greyhawkish gods, the 4e gods of Nerath, the key gods of the key "real world" pantheons, such as the Olympian pantheon, and the key gods of Forgotten Realms and Dragonlance.
Here's a list of the other 3e Domains, except for a few campaign-specific Domains. Some of these might be included in the D&D Next PHB: Others would be covered in supplements.
The God of Artifice
The God of Balance
The God of Caverns
The God of Celerity
The God of Charms
The God of Cold
The God of Commerce
The God of Community
The God of Competition
The God of Courage
The God of Crafts
The God of Creation
The God of Darkness
The God of Decay
The God of Domination
The God of Dragons
The God of Dreams
The God of Drow (The Spider Queen, a genericized Llolth. In a campaign world with multiple Drow deities, they would all assume this Portfolio, along with their other Portfolios),
The God of Dwarves (The Soul Forger, a genericized Moradin. In a campaign world with multiple Dwarven deities, they would all assume this role, along with their other Portfolios)
The God of Elves
The God of Envy
The God of Exorcism
The God of Family
The God of Fate
The God of Feasts
The God of Force Magic
The God of Glory
The God of Gluttony
The God of Gnomes (The Sparkling Wit, a genericized Garl Glittergold. In a campaign setting with multiple Gnome deities, they would all assume this Portfolio, along with their other Portfolios)
The God of Greed
The God of Halflings (The Nurturing Matriarch, a genericized Yondalla. In a campaign world with multiple Halfling deities, they would all assume this Portfolio, along with their other Portfolios)
The God of Hatred
The God of Hunger
The God of Illusion
The God of Inquisitions
The God of Liberation
The God of Life
The God of Lust
The God of Madness
The God of Meditation
The God of Mentalism
The God of Metal
The God of Mysticism
The God of Necromancy
The God of Nobility
The God of Oracles
The God of Orcs (The One-Eye)
The God of Pacts
The God of Passion
The God of Pestilence
The God of Planning
The God of Portals
The God of Pride
The God of Purification
The God of Renewal
The God of Repose
The God of Retribution
The God of Runes
The God of Scalykind
The God of Shadow
The God of Sleep
The God of Slime
The God of Sloth
The God of Spells
The God of Spiders
The God of Storms
The God of Suffering
The God of Summoning
The God of the Mind
The God of the Moon
The God of the Ocean
The God of Time
The God of Trade
The God of Tyranny
The God of Undeath
The God of Wealth
The God of Weather
The God of Windstorm
The God of Winter
The God of Wrath
There are probably also some 2e Spheres which weren't updated for 3e, such as Numbers.
Also each Portfolio (fluffy adjectives in the official description of each xD&D deity) becomes a distinct 5e Deity. For example, from the Greyhawk deities wikipedia (link):
The God of Forthrightness
The God of Resolution
The God of Chivalry
The God of Forests
The God of Liberty
The God of Humor
The God of Stars
The God of Music
The God of Oppression
The God of Slaughter
The God of Bigotry
The God of Mines
and many, many others
Only those adjectives which are entirely synonymous are combined, for example "Forests" and "Woodlands", "Pestilence and Plagues", and "Liberty and Freedom".
Generic core 5e will have many more Deities than even Greyhawk, since core 5e Deities will be synonymous with a single Portfolio.
So, each Portfolio and Domain becomes a distinct 5e Deity, but how each Campaign Setting will have a smaller number of Deities which take on the Portfolios of multiple PHB "Deities". A cleric of a campaign-specific Deity can choose to advance in any of its Portfolios. Some examples:
Pelor:
(from 3e Cleric Domains): a God of the Sun, a God of Goodness, a God of Strength, a God of Healing, a God of Travellers
(from his Portfolio fluff): a God of Light,
Corellon Larethian:
(from 3e Cleric Domains): a God of Chaos, a God of the Elves, a God of Community, a God of Goodness, a God of Liberation, a God of Protection, a God of War/Warfare
(from his Portfolio fluff): a God of Magic, a God of Music, a God of Poetry, a God of Arts, and a God of Crafts.
Mielikki:
(from 3e Cleric Domains): a God of Beasts/Animals, a God of Goodness, a God of Travellers, a God of Plants
(from her Portfolio fluff): a God of Autumn, a God of Dryads, a God of Forests, a God of Rangers
All of these would be distinct, but generic 5e Deities, with their own nickname. But in those campaign settings which feature Corellon Larethion, they would become Portfolios. Of course, other gods would share some of those Portfolios.
Only the key Domains/Portfolios would be offered as Deities in the PHB. But others would be released later.