Much of what you write would be better termed "aspirations" than "goals," as no one at WotC ever believed or wanted the rules to be fully modular (in the sense of having no core rules at all), nor did they ever think Next could completely unite the fanbase. If this were not so, then we'd see a plethora of posts this August from grognards saying they themselves had refused to convert, thus proving that the fanbase had not been united. (Or that the rules had insisted upon them having six stats or hit points or XP, when we were "promised" everything would be optional.)
I do think you captured the gist of what WotC is seeking, though. They want non-core subsystems handled through modular components from which DMs can opt out without difficulty, but don't want literally every part of the ruleset to be optional. They want each edition's style of play to be viable, but not necessarily by letting players bring their old character sheets to the table and jump into the game without doing a conversion first. And they want to bring back much of the pre-4e fanbase without losing many 4e players, which is an admittedly tall order but not quite as tall as complete (re)unification would suggest.
