I'm sorry but what I've read from that conversation is that they don't have the guidelines defined already. You can't seriously believe Microsoft will let devs make what they want in their development ecosystem, especially after saying on the press conference that nobody is left behind.
To me especially considering Shannon saying "let's talk next year, ok?" in the end of that conversation is that MS is still defining what they are going to do in the transition process, which seems to confirm the leaks about this being a reaction to Sony Neo dev kits on the hands of devs.
By the way if anyone believes Microsoft can only inform devs about their plans via their E3 press conference, I don't know what to tell you...