A False Extrapolation is a special kind of over-generalization (dicto simpliciter) involving a prediction. It is the process of predicting a result based on insufficient evidence. False extrapolations are hard to disprove because it is hard to disprove something that hasn't yet happened. What are we going to do, just wait until the prediction does or does not come true? What if that prediction won't come full circle for 30 years? Questions that could diffuse a False Extrapolation are: What evidence substantiates the prediction? and What else might happen?
The difference between a False Extrapolation and a Slippery Slope Fallacy is that the False Extrapolation isn't necessarily claiming that step A will lead to step B which will lead to step C, etc. (which is what the slippery slope fallacy does). Instead, the False Extrapolation is simply using insufficient evidence to come to a conclusion AND that conclusion occurs in the future.
Example: If cases of COVID keep rising at the 2.4 rate we've been seeing, there will only be 200 people alive by March of 2024.
Couldn't a lot happen between now and 2024? Are we ignoring regular transmission curves? BTW, I completely made up these numbers. I don't even know what a 2.4 rate is. Sounds scary, though.
Example: