One small part of the trailer shows the Dragonpriest Mask stone stand within the Labyrinthian, is it possible that we HAVE to collect Kohnarik as part of the Dragonborn quest? 'Cause i can see a pretty big problem with that: You HAVE to join certain guilds to get certain masks...

I've managed to fit an RPish way so my character does all the guilds (except he destroyed the Dark Brotherhood) but im sure some people would have a pretty big problem with that.. in my opinion people who want to RP as DB should not have go through the other guilds to get all the words and masks, i just happened to work my way around these problems with RP reasons, but not everyone wants to do that..

Im sure Beth wouldn't force having to collect all Masks upon us, but what do you guys think?

I'm not because, as you have said, you are required to complete various Faction Quests, not to mention the MQ. I have a sneaky feeling that the MQ will be a prerequisite anyway, though anything stands at this point. I may have an issue with recollecting some of the masks that I missed. Surely Bethesda won't be that mean..?

It would be cool to have a side quest involving them or maybe Konahrik, but to have them be required would be silly. I doubt you'd have to collect them. But, I would love a new side quest similar to Lost to the Ages involving lore on Bromjunaar.

I have them all I hope they'll add something extra to the DLC

I am sure it wont be a prerequesit to the MQ of the DLC but I really hope there is some benefit (like a side quest) for collecting Konahrik

With Dawnguard (no spoilers) there was a quest that was part of Skyrim vanilla, so maybe they'll do it again. I think it's unlikely because we'll be in another world-space, but it's always possible. Of course, it's much more likely that we'll be doing a vanilla quest to get to Solstheim in the first place.