So who keeps standard alignment, and who discards it?
I don't currently run D&D, but if I did, I'd discard standard alignment in a heartbeat. It sucks at doing the things it's intended to do.
What do you use instead? Does this affect the standard cosmology based upon alignment?
Dungeon World is a useful place to start. Alignment there is a "carrot" rather than a "stick": if you fulfill your alignment move during a session (which generally should be doable), you get +1 XP. (You never need more than 16 XP to gain a level, so +1 XP is a lot.) Alignment moves are tailored to each class, though there are also some generic options. For example, the Paladin has the following official options.
Lawful: Deny mercy to a criminal or unbeliever.
Good: Endanger yourself to protect someone weaker than you.
These are actionable, clear descriptors of specific behaviors. Demonstrating them earns you XP.
I have already expanded on these somewhat even in just my DungeonWorld game, and will continue to refine them. More or less, I think Alignment should
encourage players toward an ideal. And if the character's ideals have truly changed, their alignment should change! Then there's no question of whether the character "really is" their alignment or not, and the only "punishment" for not demonstrating your alignment is the failure to get the benefits of fulfilling it, rather than having to take things away.
Alignment is controversial, repeatedly shows difficulty in implementation and usage, and frequently leads to perverse outcomes. Better to start from scratch and try something else. Monsters and baddies don't need it, if they're worth opposing in context then that should be clear, and if they
aren't worth opposing other than because of their alignment jersey,
that in itself is one of the perverse outcomes.