SMT has grown a bit in popuarity here in the states, so I don't think an American version of this is impossible. As a matter of fact, I'd like to see it even though I'm not a SMT fanatic.
It's popular enough to warrent an online game but the problem is it's currently "free". Free as in no money. Simple sounding but think of how popular it is here. Atleast, think how popular Atlus is as a whole. Sure, we've managed to get a number of games from the SMT series. We got the Personal series, Digital Devil Saga, Noctorne, the GBC games, and a couple others. Problem is, we missed out on the vast majority of stuff that's been coming out and only recently have we got anything at all. During the Famicom days we got how many? None. During the Super Famicom days, same thing. We didnt get any that were for the Mega Drive, Saturn, or any other system. SMT is incredably huge in Japan. It's managed to find a release for nearly every system released there so it shouldnt come off as to much a surprise that they would have an online game where as we dont. I'd like it if we had one if not an english language patch for the currently existing one, but I do not ever see it being released here. Ever. Not in my wildest dreams or my most vivid fantasies.
What we have now atleast is playable and somewhat fun. I still think it's not a game for everyone but I think people should give it a chance to atleast wet their teeth on an import game for free. At the worst they spend 2 hours downloading a game and playing one they cant understand let alone play well. At best they find a game that sparks their interests and gives them the interest to put their money where their mouth is and start checking other imports out.