For those who may have not invested in the D&D Rules Expansion Gift Set, the relatively recent release of Monsters of the Multiverse recalibrated a fair number of monsters and playable character races (or heritages—not sure of the official nomenclature as of yet). To summarize, a lot of options were included in one book instead of keeping them scattered across multiple sources, and they have been reworked to make them easier to use in a game. Furthermore, the revisions to the playable races simply reformatted the entries into the new standard structure for that mechanic going forward: standardized movement of 30′ (whether Small or Medium sized), players beign free to have place the +2 and +1 ability score modifiers wherever they’d prefer instead of having them “fixed” to specific ability scores like Strength or Wisdom; a standard option for the character to be fluent in the Common language plus one other language of choice, rather than having them being automatically fluent in a set racial language (to account for the “dwarf raised among orcs” backstory crowd); and other notable changes.
Some see this as the soft revision of 5th ed., while others mark it as a pending shift to 6th ed. If anything, I tend to see it as 5.5 ed., enabling some revisions but keeping the basic heart of the engine in the shape it’s in. The thing is, as seen by many a gaming veteran, is that new editions sometimes have the tendency to divide the players; some stick with the old(er) edition they prefer, while others adopt or champion the latest and greatest version out there. The fact that older editions of D&D are still available for sale for those who want them acknowledges this.
I would think it to be unwise for D&D to take up a new edition, only because the current system works rather well, and really just needs correction and tweaking, in my opinion (though that isn’t necessarily shared by everyone). There’s a lot of ancillary items that feed off of D&D and in turn help feed it, such as the Critical Role fandom, so switching systems and gears may not be the wisest course at the time. But small, gradual modifications and changes may be the better approach.
There’s tons of other games out there, and they too also suffer uphill challenges from revising or updating their systems to a new one. However, as big as they are, I don’t think they really got to be as prominent or foundational as D&D has become over the years, even though they were more popular than D&D in their respective times. In many cases, the wheel has been completely reinvented, though the IP may be familiar: consider the 3 vastly different versions of Star Wars RPGs that have been released, each with their own benefits and downfalls; or, consider the various versions of licensed Marvel Comics RPGs for that matter. The IP is familiar, but the mechanics are vastly different, making them dramatically different games.
I don’t mean to sound like a cheerleader for D&D, but I do feel that the fact that it’s still around, selling well and has a relatively low number of editions under its brand name in comparison to some other games says something significant. The IP is the same and the basic concepts, structures, and play methods are the same. Is the system different from how it originally was? Oh yes, but to a degree—the ability scores still tend in the 3–18 range, rather than suddenly switching over to a 1–100 scale or an adjective scale or a a totally different set of abilities or anything else like that, which has occurred in many other games using the same IP. It may have various editions competing against itself, but at least the core concepts and some basic terminology and aspects remain the same regardless of the edition, and inter-edition player discussion is not much of an issue. Even games derived or inspired by D&D, like Pathfinder or Hackmaster (not to mention any edition clones like Castles & Crusades or Labyrinth Lord), have that familiar heart of a game system.
I don’t think I’ll have to buy a whole new set of rulebooks and sourcebooks again. I also don’t think that there’s too many problems with the game in its current form that it suffers from an abundance of errata, or is weighed down with “bloat” courtesy of sourcebooks or other sources. If anything, it’s a bit of a wash and a tune-up, but it’s the same car you love to drive under the hood.