Have an historical anecdote!
Once upon a time, quite possibly before some of you were born, there was a BBS door game called Legend of the Red Dragon. It was quite possibly the most popular door game of all time, and had a plugin system which provided for quite a lot of third-party content, allowing for each BBS to potentially offer a slightly different experience despite it being the same game. The author made other games as well, including a sequel to LORD, all of which popular and robust but still not quite as liked as LORD itself. Well one day, after several years of development, he decided to sell and move on. It was a pretty disappointing time, and a sign that the BBS world was being left behind for the internet. The company that took them over basically only did so for the money on residual sales, and eventually let some other guy continue to develop them briefly under their label, just enough to put the company and his names on it along with some bug fixes and that was pretty much it. The company has now faded into obscurity and nobody can even contact them in regards to buying copies of it, let alone buying the rights to it, which even the original author has tried to do in recent years, but to no avail.
Yet it never completely died. BBSes still exist, even over the internet, and run LORD. I ran my own DOSEmu-based one with custom scripts and everything for a little while myself. People cloned the game, too, as you may have heard of a web-based game called Legend of the Green Dragon. And similar to Minecraft, it's another of those games that I loved so much that I completely took it apart (a pre-buyout version) just to see if I could find any secrets, even though it was written in Turbo Pascal for DOS, which was a bit more difficult to do than Java code. I even ported a bit of it to C++ (but can't legally release it). But like with modding, it's a labor of love, and no matter what Microsoft ever plans to do to the game, I think there will always be those of us who still want to play it and even develop stuff for it, including years from now. Nostalgia is always a good source of inspiration.
Fun fact: The original LORD dev, Seth Robinson, is on the Ludum Dare staff these days.
tl;dr version: Minecraft isn't going anywhere, no matter how bad Microsoft could ever manage to screw it up.