Indeed, that should indeed be the goal but it’s not realistic to expect it to happen overnight. Rome was not built in a day, and neither were most church buildings.
However, bishops who are finding that ordinariate clergy are filling critical gaps in their own dioceses might not be so eager to have that happen. What exists in the Personal Ordinariate of Our Lady of Walsingham seems to be a very healthy collaboration with many of the dioceses where the ordinariate is active. By way of example, the situation mentioned in my previous comment in which an ordinariate priest serves as the pastor of both an ordinariate congregation and a small diocesan parish frees a diocesan priest for another assignment!
Incidentally, I hope that the Portsmouth Mission is growing in a manner that will allow it to become a “parish” in the not to distant future. That congregation already has full and unimpeded use of a church, though a secular charity technically owns the building, so it should be just a question of numbers and financial self-sufficiency.