Well, it wouldn't have to be them, necessarily. It was said that they designed all the new sequences so they could be rendered at film quality. Ideally, they'd be able to reset all the compositing to the higher resolution as well, so it'd just be a matter of rerendering and swapping out the old versions. Of course, having seen that Enterprise model in high resolution prints in the intervening decade, I can say film quality in 2000 is not half as good as even some TV quality in 2009. They'd probably want to do some additional tweaking if they wanted to do it right (ha!), but it should theoretically be possible to just pull the old files out of the archives and up-res the lot of it.