You have to do a lot of work to support subsite semantics so
I think it will always be "you are or you aren't".
Right now it means 15 or so paramters (maybe 5 important),
and supporting the expected url space:
image.vuh members.vuh pvt.vuh register.vuh shared.vuh user.vuh and admin,
navigation stuff, and callbacks to create the application group.
We could make a lot of this "just work", eg the application group creation could be automatic, the paramter set could be made smaller, and the url space could be trimmed (e.g. we could make user pvt and shared packages) which would make the changes needed to make a package "subsitable" easier.
I'm not sure we want to go through all that though as mostly what you are shooting for is selectively trimming off current acs-subsite features and replacing the odd bit here and there.
It's still a "subsite package" rather than a package which does a bunch of stuff besides what subsite does.
