So let's see what you consider incremental change to BX and what not
1) not having races as classes
2) removing racial class limits
3) adding skills and feats
4) adding cantrips to vancian casting
5) unified XP progression
6) subclasses
Remember the evolution analogy. The key with incremental changes is not that they can’t lead to a large departure in the end, but that you never have so many of them at once that there’s a clean break.
BX 2023 probably looks nothing like, and is incompatible with, its distant ancestor BX 1981. But 81 was mostly compatible with 83 and 91 (in real life), and our notional BX 23 would have been mostly compatible with its closer ancestors.
Race/class split? Both Labyrinth Lord and OSE already did this in their “advanced” rules, without changing the underlying BX chassis.
Removing level limits and unified XP progression? I feel like there’s at least one retro-clone that does that already.
Rules Cyclopedia added skills. There are all manner of third-party BX “feat” systems. (Remember, while in the AD&D 1e days Gygax liked to maintain strict control over what was “official,” even TSR’s own magazines would publish a vast array of new classes, races, spells, magic items, and even optional system bolt-ons. The thief, paladin, ranger, druid, and illusionist all started as magazine contributions before becoming mainstream D&D. Heck, the Rolemaster RPG started as a set of plug-in replacement combat and magic rules for (A)D&D. If that ecosystem and the general ethos of “tweak the system to fit your table, we sure did” is allowed to persist alongside the incrementally developing BX, that changes things considerably.)
Cantrips were an Unearthed Arcana add-on to AD&D, previewed in Dragon. They weren’t significantly damage-dealing until 3e and didn’t become the round-by-round go-to of spellcasters until 4e and 5e (with the late-3e warlock as a precursor). Shouldn’t be too hard to add (though we should note that this alternate history is presumably not required to result in the same changes seen in our current D&D — incrementally modified BX might follow a different path away from fire-and-forget magic.)
Subclasses? I know of at least two OD&D clones that offer them, and Dyson Logos had a set of BX ones on his blog years ago. Heck, “subclasses” were what the paladin et al. originally were, and of course BECMI made some of them into proto-prestige classes, so it’s literally been done as incremental change to an existing game already.