It seems that Ubisoft revealed during their financial call that it invested heavily to make sure that all their brands could become multiplayer.
While he didn't state directly that this would be their policy indefinitely, they definitely made it sound that way. Apparently they're also focusing on trying to have both competitive and co-operative multiplayer in all their games, but mentioned that co-op isn't in all their titles.
They also implied having local multiplayer as well, which is good news for fans of splitscreen.
I transcribed the relevant section below, minus about 5000 "uhs".
Originally Posted by Ubisoft:
Now on the multiplayer side we made yet big investments to make sure all our brands could become multiplayer. So we will come with Driver, that will be mulitiplayer, with Splinter Cell, will be multiplayer, Assassin's Creed as well. Ghost Recon is also multiplayer. And in the multiplayer we don't only do one side of the multiplayer, but also co-op most of the time. So those games will take full advantage of the ability to play with friends either via the internet or at home, so we are putting lots of emphasis on that subject to make sure that our games can be played by more people together, and we also consider it a key factor for the relationship we will have with our customers on the more long term basis. That's why we also have UPlay on the other side to connect our players to us, and it will allow us to do more DLC on those franchises in the meantime they wait for the future release. And the more we go the more we think we will have a more permanent relationship with our customers thanks to a certain number of downloadable contents and relationship via UPlay we will have with our customers. So that will make us have a constant relationship with our customers.
[It starts at 18 minutes in]