Yes, as
@Steve Withers said on the podcast, they may be shooting for:
1. TMP + Genesis Trilogy (4)
2. V-Generations Crossover Movies (3)
3. Next Generation Trilogy (3)
Which, as you say, makes it easier to get them out in time for the anniversary AND not put people off with ridiculous price tags.
I'd certainly feel happier paying £80 now and £60 end of year, and another £60 next year, as opposed to £200 now, even if they add up to the same thing. And many may wait for the latter two sets until they drop anyway.