Eh, I don't think that "point X" language clarifies anything. We have seen people mix and match the new rules with the old at the same table, but they are also at the same time clearly revisions and not errata.
I jest.
But...
A few years ago, around the time there were at least speculations and rumors of the 50th but before official announcement, I made a poll here asking where the likely 50th anniversary edition would land on the ".x" scale. I think I described them like so:
5.1: Errata and new art, covers, and formatting, but no actual rules changes.
5.2: As above, but more significant re-formatting, minor rules adjustments and clarifications, maybe a few new options.
5.3: As above, but moderate rules adjustments and new options, but still mostly backwards compatible.
5.4: As above, but more significant adjustments, and probably the need to replace the old with the new in some cases.
5.5: As above, but with some major rules adjustments and options, if with the same basic chassis.
6.x: Actual new edition (e.g. 3.5E to 4E or 4E to 5E).
Or something like that. It sounds like 5.2 is most likely, with 5.3 being possible - but definitely more than 5.1 and probably less than 5.5.