If online poker became illegal, could the feds do THIS???

[PokerPaul]

with all the talk about the US trying to potentially illegalize online gambling and poker (which i do not believe will happen)...but if they do, this is one way they could enforce it, unless i am overlooking something:

Unlike with napster and the music industry, it may be possible to cutoff the pokersite traffic, since all the pokersite servers have a distinct IP address.

If the feds were to simply order all the ISP in the country to prevent people in the US from connecting to those blacklisted IP addresses, wouldnt that shut the whole thing down??

What could the players or pokersites do about it??