I thought about this a bit, to try to give an honest answer (rather than deluding myself into thinking I'm more inclusive than my feelings really are).
It's important to me 5e that it supports the majority of D&D players from past editions.
It's not important to me that it supports components that were exclusive to either 3e or 4e at the
expense of supporting multi-edition standards. I don't think there is usually going to be a need to choose, because of modularity.
In general, I think that 95% of players (and a somewhat smaller majority of DMs) are going to get basically what they want enough to be interested in switching, and that rarely are sacrifices going to need to be made.
Specifics:
- I'm not willing to sacrifice the Planescape/Spelljammer unified cosmology as an officially supported and fleshed out option that include relevant rules for using it in all the standard campaign settings to which it was originally connected with (Everything in 2e).
- I am willing to sacrifice that cosmology as a default option.
- I'm not willing to accept 4e setting displacing previous edition setting (including presentation of core subraces and classes).
- I am willing to grudgingly sacrifice my "purist" desires to allow core modular inclusion of some innovations I don't like (such as 4e added races), because others do want those.
- I am not willing to sacrifice what I consider distinctive features of D&D (traditional races, classes, alignments, Vancian casting, etc) to make it what I objectively confess might be a better game. I want the best D&D, because there will, IMO, always be better games out there than D&D, but there shouldn't be better D&D out there than D&D.
- I am willing to sacrifice pages of the books to rules I don't need or want to make happy people who do want them.
- I am not willing to sacrifice what I feel is the "essence" of pre-3e D&D for a wider audience.
- I am willing to accept support for some of that essence relegated to modules.
All those considerations aside, I honestly don't care if the game continues to publish new product after establishing the basic material that I want (which includes core, old-school campaign settings, rules for planes, deities, psionics, oriental adventures, and mass combat).
I don't believe the hobby will collapse if D&D folds. As long as I have friends willing to try this "role-playing thing," I don't care about the popularity of the hobby.