I have not read through this entire thread, so forgive me if I repeat things others have already said.
I am mostly familiar with the Forgotten Realms setting (though I am a Critical Role fan, too), so my thoughts will mostly be directed at Toril. My thoughts will also mostly concern lore, as, while I am very much invested in the setting and D&D, I've only actually played a few times, so I can't weigh in that much on any mechanical aspects.
With regards to orcs and drow at least, in the Forgotten Realms, actually already have an example of goodly drow and orcs. Eilistraee, the daughter of Corellon and Araunshnee/Lolth, has been present in the lore for a long time (I believe she was introduced in '91). She has been providing an alternate path for the drow for centuries. Likewise, Vhaeraun, her brother while "evil", is still a better choice than Lolth.
In 4e, WotC killed them off, because they wanted Drizzt to be the "one special drow". Kind of shot themselves in the foot there. Eilistraee and Vhaeraun were returned in 5e (having it be revealed that they in fact never died, but instead were held in stasis in the Weave for a time). Her followers were mentioned in Ed Greenwood's Death Masks, and she and Vhaeraun are in fact allied now.
There are also the Ondthi orcs, who I myself only recently learned of, but they have been around since 2e. These were goodly orcs who follow the deity Eldath. Unfortunately, they've been largely ignored, as have Eilistraee and Vhaeraun, even though they've been returned. I think if WotC/Hasbro looked to established lore, rather than changing everything, it would at least give them a start (at least in this area). I hate Lolth, but I wouldn't necessarily want her or Gruumsh to be killed (there was enough deity death in 4e). But she could be reduced in power, as more drow turn away from her and towards Eilistraee and/or Vhaeraun. This would bring back lore that has been around for years but brushed aside, and reduce the risk of more retcons.
I'm all about diversity and inclusivity. I just wouldn't want the "culture" of races (or species I guess) to be diminished (elves have a culture, dwarves have a culture, halflings have a culture, etc, especially in areas that are heavily populated by that race). That doesn't mean these cultures can't evolve, of course (and a halfling raised by orcs, rather than other halflings, may act more "orcish".)
I will admit that I am big fan of the gods (I know some people have issues with how involved they are), and I enjoy settings with well-established afterlives. This is kind of why I have stayed away from Eberron and Dark Sun--from what little I know, the settings seem to the deities far removed, and the only option for the afterlife sounds pretty grim. At least other settings have various options.
I'm honestly not sure what to think of the alignment thing. Would the change only affect the mortals? If it's based on choices--which it kind of already is--a person goes to the plane based on how they lived their life (so a person who has made evil choices would go to an evil plane, for example).
