I'd have thought that one of the final updates will be to remove the requirement to activate.Even if they could do that (I don't think they will) you need running XP to install an update. I know I can try to play with nLite and slipstream all patches BUT it has real problems with Polish Windows version which I have.
In theory: you've got 30 days to activate but it has never been working for me. If I skip activation during install I have no chance to do it later. It is always saying right after installation that time to do so ended.
Perhaps they could make an official patch available; you'd just need to take care to keep it in case of reinstall, though it's possible a copy or two might find their way onto the web
Or they just set their servers to automatically validate anything, even if the code is 1AMAT 413FA ND15T 0L3T4 15XP1
Please, please don't try to validate with that code