I like that idea of splitting the update, Minecraft did a similar thing. Furthermore, this update is simply too large to release all at once and come out of early access. I would recommend that the community is allowed to give input on the at least part of the update before KSP is fully released (hence splitting the update). There have been accidents in the past which could be harmful to KSP's reputation for a 1.0 release, for example asteroids and the claw part from .23.5 were completely broken (in fact, they are still broken to this very day), and in .21 the new SAS was not quite what everyone wanted (was fixed in patch). As GusTurbo pointed out, there would be too many bugs.