Just my two whispers:
1. If they have Malkavians as a starting clan, how much work would they have to put in? Rewriting dialogue, NPCs reactions, whispers, maybe add some hallucinations here and there.
2. If they have Nosferatu as a starting clan however, they would simply have to enforce a certain playstyles: hiding, traveling through the sewers, not making contact with NPCS as that would be a masquerade violation etc.
It seems to me that, Nos would be much easier to implement than Malks, the amount of work would be normal or minimal compared with the other clans. So I think that Nos may be one of the clans and Malks would be DLC. As long as we get both though that's all that matters.