I'm really old in Internet years (just turned 44), but doesn't hotseat = only have one, non-networked PC to play on? I mean how is the seat hot unless someone else's butt was there right up until yours was?
Maybe it means two people playing on the same computer can both play online with other people, as well?
I still have no idea if I'll want to do much with multiplayer anything, but hotseat vs. online seems like asyncrhonous vs. synchronous to me, and I'm really hoping that if the game has to pick favorites across a division like that, then the asynchronous multiplayer people will be the winners.
I'm completely the other way around. Synchronous multiplayer >> asynchronous multiplayer. For one, it gets rid of the turn order advantages/disadvantages, and more importantly it makes games go SO much faster, especially as you include more people in the game (synchronous is about x times faster than asynchronous, where x = number of players). As far as I'm concerned, the only reason to include even the option for asynchronous multiplayer is so that hotseat would actually be possible. And if hotseat isn't important to very many people and balancing/designing the game with both modes in mind turns out to be painful, then I'd vote that they even drop hotseat.