As long as it's not too expensive, it's exactly what a lot of prosumers might want (especially those who want to ditch their laptops for iPads and iPhones, and maybe a MBA for the road- a lot of people's MacBook Pros live on their desks). I can't see a serious video editor wanting one, but they're all jumping ship to get cheaper Wintel workstations (and at some point, studios will move the heavy lifting to some kind of local big-iron server).
I can see developers who want a slightly better machine buying it, and rich people, and photographers, and so on. If Thunderbolt expansions bring down the costs of upgrades (compared to buying the upgrades with Apple - not everyone likes to open their chassis) then it might be quite attractive.