The IPv4 systems that need to be updated - the hosts - will not be. Not in a year, not in ten years. This plan is a non starter.

v4 should, at this point, basically exist as fallback prefixes for the devices that will hang around the next 30 Y without proper v6 support etc.

Routing in the small is not hard. I am absolutely baffled that people are claiming BGP is some kind of super hard thing to deal with. BGP has a ton of problems and lots of ugly duct tape (rpki, etc.) that is just done poorly but it isn’t hard.