well you wouldn't have to put fake whois info if the US passes such a law and you aren't a US citizen.

ICANN might technically have the ability to seize a domain with bad WHOIS, but in practice, they don't get involved with individual domains (hence the Registerfly debacle.)

HOWEVER, there are a ton of horror stories of GoDaddy and some other less-than-reputable registrars grabbing domain names and selling them for bad WHOIS info, so this is sometihng the individual registrar, not the registry or ICANN, would be involved in, unless the rules for .xxx are different than for other TLDs.

The rules about whether porn has to go under .xxx would be ones enacted by local or federal governments, ICANN wouldn't have any jurisdiction in this regard.

from what you are saying it is implied that foreign affiliate webmasters have very little to fear from this whole .XXX issue as they will be affected only indirectly, they can still use their .com domains

Well, that totally depends. If the US, or even certain states or localities within it start requiring the use of .xxx, which seems likely, I'm sure that governmental leaders in many other countries will follow suit. Likewise, unless your traffic is entirely non-US and going to non-US sponsors, it will have an effect on you.

This is one of those things that a lot of governmental people will just line up and do... how many legislators are going to stand up and say "I'm in favor of the rights of pornographers? Probably not many.

Forewarned is forearmed. You can put your head in the sand and say "It won't affect us" but that's a very shortsighted approach, and I doubt you'll be happy 3 years from now if you do that.