i'd assume daemon summoning would have been planned for a long time - but probably won't be in till after launch. as for creating your own chapter that can be taken many ways, for me i see it as being able to give a color/shoulder symbol that's synonymous to your guild.
I think you misunderstand how "canon" works in 40k... I recommend dialing back expectations in this regard, by a lot - it's much better to get positively surprised later on, than being devastated because expectations were too high. It doesn't mean that one should not strive to advocate one's opinion on the direction the game should take, of course, but already it is safe to say that Eternal Crusade will make various concessions to gameplay much like THQ's Space Marine did. And I'm sure to many people this will even make it a better game. For example, many Marine fans will probably be delighted to hear that EC-Marines will apparently be 8 feet high as opposed to the codex-stated 7 feet. Speaking of devastation, I would consider Devastators being the "repair guys" a much more critical issue than various homebrewed Successor Chapters making their apperance. Ironically the latter would actually favour GW's original background in that it would mean fewer players in the four official Chapters. That being said, I have a feeling that this might actually just be a big misunderstanding because something got "lost in translation". English is not his first language, after all. Perhaps what Miguel meant was more akin to guilds where you can create your own companies (as part of the four Chapters), with a limited influence on their armour appearance?
Those views are partially contributed to the fact that TenTonHammer made a bitchy article towards bE and Angry Joe when it was supposed to be an informative article pertaining to EC @ PAX. Edit: The link to the article in question: http://www.tentonhammer.com/preview/warhammer-40k-eternal-crusade-things-can-only-get-better-here Reuben has since that article posted a more neutral article concerning EC but he made the same mistake of not covering anything in detail in the article so its not really worth a read.
Also you should stop turbo nerding and realize that TT Rules do not match Gameplay Flow. It never has.