@HonkHonkBoom >give the the option to keep using the old one without freaking breaking it.
This is one of those things that every UI overhaul should consider. They obviously don't care about bloat, so the extra storage and maybe RAM needed should be NBD. You let people choose, and if most people are on the classic UI, you start slowly tweaking your new UI and put a highlight on the update note in app (UI - changed X feature to resemble classic UI functionality) and see if that changes things.

My biggest criticism of modern UI is abandonment of "Network" and "Table" based UI wherein components from one node can link to or be access from another node, like vines allowing you to swing between branches on a tree or comprehensive list of choices that fall under a category. Android actually was moving toward this correctly for a while but has moved away from it in favor of copying the iOS tree rigidity without consistency. I want them to make things take less clicks to get to and suggest possible alternatives that make sense (NOT the garbage way that Microsoft does this).