Firstly, no matter what jaded ideas anyone gets, it will take a very long time lose even half of the 7.6 Million subscribers that play WoW. WoW also isn't going to pull anything like the dreaded NGE for SWG, as experience is now their guide for further game development.
An expansion like this isn't a cash grab in prep for a fallout. The "jump the shark" expansion would involve fighting Sargeras. If anything, it seems like WoW is going back into it's roots of innovating ideas from other games; and cutting them to fit their design philosophy.
I lovingly called this "The EQ2/Guild Wars Expansion" to my wife... halfheartedly of course.
They talked a lot about "kits" at the con, which shows they're admitting WoW's aging. I believe that their intention is to get ready to pump out more expansions faster after WoD; more than likely geared towards individual racial issues. It's not uncommon for a game studio to use culture kits to quickly make themed expansion content... it's just been uncommon in WoW till now.
I really don't think they'd use such poor judgement as to wait a year to release WoD. Especially after dropping the bombshell that there will be no 5.5 release.
Finally, the whole "Jaded WoW Player" mindset is a common cliche now in the MMO world. I feel a lot of the "WoW is doomed to a slow death starting now" talk comes from a lack of WoW players enjoying other MMO's as well.