Issues around "compatibility" and "canon" seem to apply only to people in one or both of two groups:
1) People who play in public games.
2) People who play the rules-as-written.
I've never been in either group, so such changes don't matter to me personally, although I can see how people in either group would be particularly irked--or at least inconvenienced by changing things up. At the same time, an actual edition shift every 10 years--and micro-changes along the way--isn't all that big of a deal, especially when compared to the history of D&D. Even if the 50th anniversary is an actual new edition, or even "5.5," having to buy new books after 10 years shouldn't instigate armageddon.
I suppose I fall into a third group:
3) People who prefer when WotC publishes stuff they're into and/or can use in their home game.
So on one hand, I can say that I could be disgruntled by the fact that WotC is veering in a general away from a game that I'm excited about, but combining two facts--I don't have an active game right now and there's lots of other RPG material I'm interested in--this is not a serious issue. If and when I do start a D&D game again, it might become an issue, although even so, there's still tons of past material to use, and I always have the limitless power of my own imagination to draw from. But even so, I do prefer that WotC publishes books that I can't resist picking up to browse and gather dust on the shelf, but on the other hand, as someone approaching half a century, I don't expect them to have me front and center in their publication plans.
As far as the specific orc content goes, it seems that people fall into one of two camps, though it is really a spectrum: Those that see the removed material as problematic and thus applaud its removal, those who don't and thus don't like it removed (and all those in-between that see it as some variation - anything from "a wee bit problematic, but not a big deal" to "not problematic, but change is good", etc etc).
Either way, I do hope that WotC emphasizes the non-moralistic element of such changes, that this isn't about pushing a particular ideology of how everyone must relate fantasy and reality, but more about broadening the scope of (for example) orcs to reflect a wider range of options, which in turn reflects the last 40+ years of different stories and games told about orcs. Meaning, we don't have to get into the endless debate about whether or not orcs represent a real world people, and thus whether or not their past depiction was problematic (let alone to what degree, and which depictions, etc), but simply the basic fact that we've had decades of orcs that have been depicted in a variety of ways, and many people approaching the game now like flavors other than Tolkien or Gygax. But part of this might also require saying, "If you want Tolkienian or Gygaxian orcs, that's fine too, because this is a game of fun and imagination, not a curriculum on real world ideology."
Similarly with Asian/Oriental Adventures. The emphasis can be less on, "If you want to play mid-20th century Westernized media depictions of Far Eastern cultures, you'er a bad person," and more on something like: "the West is less insular now than it was 40 years ago, and there's just more intermixing of different cultures, so we can now depict a wider and more accurate view of non-Western cultures."
Which brings me back, again, to a place that I wish more took for granted: D&D is a game that you can customize to your own liking. Orcs can be brutish half-men if you want them to be, or they can be as diverse and sophisticated as human beings. It is really up to you. One way WotC can model this is by using the settings to explore different variations on the theme. This would mean that each setting doesn't have to include everything from the core rulebooks, and can vary quite a bit.
That said, I am skeptical of whether WotC would take this creative approach, as they seem to veer more towards making every world stick relatively close to the core rules. This is not to say that they'll include starwhispershadow elves in a hypothetical Dark Sun setting, but that they might not go all the way in on the possibility that the core sub-races simply don't exist on Athas, that Athasian elves are their own thing - which, again, would be the creatively optimal approach (imo).
SImilarly with racial ability adjustments. They can market it as, "this is a way to make the game more customizable" rather than "this is a way to make it clear that a halfling can be as strong as a goliath, and if you think otherwise you're x-ist."
Not everyone agrees on what is or is not "problematic" or "x-ist." These are ongoing conversations, and socio-cultural norms are ever-shifting; what seems progressive or edgy today, might look backwards and outdated in five years. WotC could relatively easily work around this by emphasizing the actual in-game elements, such as making the game more customizable, but also not being afraid of providing contextual examples (e.g. Dark Sun elves that really fit the milieu, or "the orcs of Greyhawk tend to be...") that differ from the core rules. The game would only be richer for it, imo - and it strikes the best of both possible worlds: it disentangles the core rules from narrow stereotypes that some find objectionable, but also broadens and diversifies the game and, most importantly, still is a game to which everyone is invited to play.
