El Mahdi
Muad'Dib of the Anauroch
Excellent points, and an excellent thread subject.
I think that the core system they make needs to absolutely "feel" like D&D...and only D&D. And has to have the modules necessary to make it "feel" like any specific edition of D&D. But I also think all of the ideas that could never be explored in D&D because of this limitation, should now be attempted, though in modular format.
To not explore things that may not "feel" like D&D with D&D Next, would be a waste of an incredible opportunity.

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... would help to go back and reread the OP before responding. My bad. Posting in too many threads and lost track. Sorry about that.