Coffee shops were once new, novel, exciting. They haven't gone away. They are still here. But we don't talk about them as much, we just quietly patronize them.
That will likely happen in craft beer too. Calling it a bubble implies that established breweries are going away, that people will stop drinking craft in favor of swill. Not likely.
Breweries will continue to join the party in Minnesota as more and more people discover craft. The expansion will stall once people stop converting, but Portland tells us we have a ways to go here.
Once a craft beer drinker, always a craft beer drinker. We will continue to support our local craft brewers into the future.