BasilZero said:

Could be that the next SMT mainline game is the last one :O

Then they will go ahead and make more spinoffs!

The game has been announced now, but just for future reference, a company will rarely ever announce that a game will be the final one in a franchise like this, where they're not all linked by one story that has to end at some point.
Because you never know if you want to make another one at some point in the future, so it would be shooting yourself in the foot for no good reason to make a claim like that.