In my humble opinion, I believe that it would be a horrible idea if they made "Watchmen 2". Frankly, I doubt that Watchmen 2 could live up to the original. A TV show could work if it were to just expand some parts of the book that didn't get much time/no time in the movie (i.e. "Under The Hood" which I thought was poorly done in the special features of the Watchmen DVD).
I especially don't want them in mainstream comics because that would just be a bad idea. Having Rorschach travel to another Earth just wouldn't fit with the Watchmen canon.
The main reason though is because Moore doesn't want it. If the creator doesn't want it, then it shouldn't be done.