I know that certain people (see above) say there's no way it would have happened, PR-risk, etc. But I'm not so sure. Obviously, in order to make any blockbuster trade with your provincial rival, it would have to have been a really good trade from Montreal's perspective, one that was too good to pass up. Given that it was a favorable trade (it wasn't in reality, as we know), I think by '95 Montreal would made a deal with Quebec.
I mean, it's not like Montreal's PR didn't suffer a massive disaster anyway by trading Roy in his prime and getting a couple of okay players back. In the imaginary scenario, better to send a Hall of Famer to Quebec and get better value in return.
Gretzky was traded to Edmonton's division rival and faced his old team 15 times his first season there (and eliminated them from the playoffs). Guy Lafleur ended up playing for Quebec when he was old -- wasn't exactly good PR for Montreal when they basically forced him to retire prematurely in '84.
I'm not saying it was probable, but I think it would have been possible (if the return value for Montreal were better, that is).