Dragon's Dogma Online? I can dig it.
Now the games availability will depend on its success - if it does badly, they'll take the servers down, and you can't play it. If it does well, you can play it, but only until it does badly.
Online only is terrible for games - it "works" if it happens to be a game that a lot of people like, and is supported well, like World of Warcraft, but that's rare, and is completely different from this, since this is on consoles, and probably not a fully fledged MMO. If the graphics are any indication, it'll probably have a staggering budget, and since MMO's also require monthly patches, it'll likely require some sort of subscription fee -- which means that it would cost an extreme amount of money and require tons of players.
But MMO's, or games that have servers with thousands of players, don't have physics (In regards to enemies.) like shown in the trailers for a reason - bandwith, internet speeds, etc.
The internet part will probably be limited to some sort of multiplayer lobby, and work like Diablo 3 - which would mean that the internet part isn't really necessary, and it should have an offline modus as well.