I expect with a company the size of Wikipedia, particularly one with Wikipedia's web presence, switching your hosting around isn't really something you can do on the turn of a dime.
On the other side of the coin though (er, so to speak) i wonder if this is really the best tactic. I mean, i couldn't wish for the fallout to land on a more deserving company, but will this affect Wikipedia's bargaining position for similar situations in the future? Threatening to punish people for actions you don't like is just fine (well, assuming you stick to legal methods of course) but if they recant and you follow through on your threats regardless, would the next company you deal with have any reason to recant?