This is the slippery slope fallacy.
The play happened because the opposing team neither flushed the guy behind the net nor adequately covered the front of the net. It was a perfect storm of the defending team just standing there, watching the puck, and the offensive player saying "Screw it, let's do something cool" AND having it work (not just the flip over the net, but an accurate tip in of a falling, tumbling puck). There's 0% chance of that play becoming commonplace simply because the likelihood of all those things happening in a predictable, repeatable way is so low. There are too many variables that need to align just so.
Moreover, if it somehow, miraculously, does start to become commonplace, then teams will begin to account for it and defend accordingly. Like any sport, hockey is about adjustments. If the league adjusts one way (these kinds of plays), then it will adjust back (making them far more difficult to execute).
