A redesign is the occasion to keep the existing visibility of the website and make the most out of technical resources to start with better & saner SEO bases. It is an ideal time to fix all existing blocking issues in order to significantly improve performances.
Impacts on visibility:
Impacts on investments:
Impact on your support:
Impacts on the popularity of the website (link-building)
Warning : Good framework and processes are required during the creation of this website in order to avoid any new arising issues. The main risk being losing the old website's visibility and not getting as much with the new website.
Example of SEO visibility evolution before/after a redesign project that is properly managed, allowing the number of keywords to grow after the redesign:
Example of SEO visibility evolution before/after a redesign project that is NOT properly managed, causing significant loss after the redesign for the existing SEO rankings - without mentioning the important delays and the necessary efforts it will take to come back to the previous level