I don't know how to spell this out to you anymore.
I'm not saying MK9 or Injustice is still going to exist in 10 years. I'm saying the opposite. They won't exist competitively. They'll die for the same exact reasons I said Melee will eventually die by. If not in 10 years, later but inevitably, they'll be old consoles that won't work anymore, that aren't made anymore, and therefore can't be purchased for new players. Of course the tournament scene is going to die.
The difference is although the game dies, the community doesn't. The Capcom, NRS, and Namco communities just move onto the next game released, because the developers have an active interest in keeping the franchise alive, by adapting it for the times and releasing it on new hardware. Either by re-releasing old games, or releasing new competitively balanced games- either way, the community lives longer than the game.
When Melee dies, it's pretty much over. Unless Nintendo takes an interest in supporting the competitive scene, there aren't going to be new competitive Smash games to play. There's nowhere for the community to migrate to that still has the gameplay they love. They can't migrate to the newest iteration like other communities. Their lifespan is literally dictated by how long the hardware can hold up.
The very EXISTENCE of Project M is basically a recognition of this. In order to keep Melee going, they have to retrofit the newer games, because Nintendo isn't going to play ball and balance the new game for tournament players.