perfect fossils = gone
beast 30qual corrupt = gone
tainted quality = gone
possibly still 30qual bases from mobs but they wont drop special bases and that may be removed because it generally would not be in patch notes
They may have or may at some point add a way to go above 20% quality on an item but as far as the patch notes indicate it seems sources of adding quality above 20 are all being removed
(if you have any phys weapons i suggest you quality them now, there will be new bases for armour but i guess still worth if you have anything you care about)
side note: Apex Cleaver's will be going good legacy and you can easily generate 30 quality bases with necropolis , the implicit and

