Momo You are jumping to conclusions there. Although it's true we can't be sure that Mira will be revisited, it's too early to think that a new IP we barely know anything about could replace X. It was pointed out that the setting/genre seems to be completely different, and Takahashi has been trying to make an space opera for so long that I doubt he'll ditch all the lore he wrote for X's universe. Kojima seems to love the genre too (and he's probably one of the guys pushing for "western sensibilities" at the company).
Devs usually iterate on the same systems/ideas in different projects. "Sidequests", "NPCs in towns" and "Mechas" are things you'll probably find in the majority of their games in the future, so they don't really tell us anything of substance about the project. Online functionality is nothing easy to implement - and the way they did it in X was probably limited in comparison to what they wanted to achieve - but they have a foundation now and they'll probably improve it in their next games. Action is something they've been trying already in things like Disaster.
If this project potentially replaced the X sub-series, not even Monolith knows at this moment. Although it would be fun if at the end of the medieval tale you're told that humanity appeared in this world hundreds of years ago after a war/experiment. They've only done it a few times.
