That plugin sounds very useful!

Being able to "roll forward" is very clever, and could be super helpful. Let's say you end up working on a site with WP 3.1 or something. A plugin is now 10 versions behind, but its Magical Database Overhaul occurred 5 versions ago. You update, and it's just trashed - the Magic Overhaul had the Magic Conversion! But if you had this "roll forward", potentially you could gradually update, testing each step, and coming out clean!

Another minor issue this could solve is when you update a plugin but find that the new version only runs on PHP "7.whatever", which is not on your host yet.

Nice job!!!!
Dave