I don't think there's the revenue growth potential in Minecraft like there is in Instagram. On the other hand, Mojang made $330 million in revenue and $129 million in profit last year. They can probably hold on to those margins because their sales system doesn't share revenues with retailers or distributors (or Valve, Google, or Apple for that matter).
The interesting question is whether Minecraft has legs to continue selling for ten or twenty more years. I think it might. I know lots of parents that don't let their kids play video games except for Minecraft. When I pick my kids up from school, I always see a handful of kids wearing Minecraft shirts and carrying Minecraft lunch boxes. It could become like Lego--a toy that's viewed as educational and beneficial by parents.
If I was Microsoft, I'd do two things: First, I'd work on performance and clean up the presentation a bit, especially on the loading screens and menus. Second, I'd roll out a service to make it easy for parents to set up a locked-down server for their kids. You wouldn't believe the number of parents who have asked me for help in setting up a Minecraft server for their kid and his/her friends. I finally stopped showing them because it's too complicated for them to keep running. A service that cost $4.95/month and was reputable, simple, and secure could make a killing.