If they don't put all 8 specialties in at launch, they'll have a riot on their hands. Wizards have had 8 specialties for dozens of years (before 4e). It's not just mechanics, its woven into the setting and philosophy of pre-4e spellcasting. If you notice, the current spells still use all 8 schools. Not providing specialists for all 8 of them would be a travesty.
But I don't think they will do that. I expect we will have all 8 in the PHB.
As far as generalists...well I sent Mike Mearl's a tweet on it a couple weeks ago, just to see if his position had changed, and I didn't hear back. So my guess is that they are out. It's sad, because I foresee a lot of groups houseruling them back in immediately. They really should anticipate that and just make the darn subclass.