Lol, quite possible.

In any case, unless there are websites which look exactly like bitcointalk does and can somehow trick regular bitcointalk members into attempting to log into them with their credentials, I don't see why it's a big deal.  People shouldn't be using the same login details across forums anyway, so even if people were to register on a clone site (or one that's close to a clone), hopfefully they wouldn't provide enough info for their bitcointalk accounts to get hacked.

And while we're on the subject of other forums where crypto is discussed, I'm pretty sure most of them are dead at birth.  Unless a site can duplicate the signature campaigns and bounties, which are a feature almost exclusive to BCT they don't have a snowball's chance in hell of succeeding.  Not sure what the state of cryptotalk.org is right now, but even with members getting paid 1000sats per post, the site was a mess of spam and otherwise nonsense posts.  Bitcointalk has more or less a monopoly on the market for discussion boards about bitcoin--and for good reason.