The game sold over 70 millions since the buyout. They got tons of money from microtransactions too. It was licensed out for other games, books, a movie is coming. It is a gold mine as far as gadgets, toys and other merchandising go. Streamers still play this insanely much, YouTube presence is as big as ever. It is a cultural phenomenon. It is being used to push technology like crossplay, Hololens and more. It inevitable sells hardware (not only consoles but other Windows 10 devices too), even more so now that Sony decided not to join the Better Together update.
Minecraft is huge, it will probably become the highest grossing game ever despite the low entry price. Anything these guys make after this will have an insane amount of publicity. And guess what, it's a brilliant Z-plan. If all else fails, announce Minecraft 2 as a launch exclusive for the new Xbox and see Microsoft win the console war before it even begins. I think most people don't quite see how big Minecraft is. It is simply insane.
If all else fails you don't make it exclusive. You get it into as many hands as possible.
Look at what they did with Office for smartphones.
If all else fails, watch they make Better Together and later updates available to Sony's latest console.
I agree with what you're saying, but at the end of the day money talks...