When they were mentioning factions at the end of the gameplay video, he didn't mention anything about about a Morag Tong / Dark Brotherhood type guild. Then again, are those two even considered factions?
I'd be very sad if there wasn't an assassin's guild to join. :(
Anyway, playing through Morrowind pretty often to suppress my excitement for this game. Morrowind is good but I'm not sure it has aged well, especially to casuals who loved Oblivion like me. Still enjoying it regardless, because I've seriously played Oblivion so much I could probably play through it with my eyes closed.