Why ruin a perfectly good trilogy with a 4th film?
The whole setup is gone. The next film would be John Blake vs. the Mob, with a little help from Fox when the Bat-Wing needs fuel.
Silly question - because a 4th film could make a shed load of money and will do nothing to diminish the pre-existing trilogy unless they really screw up and kill the surviving characters from the earlier movie in the opening scene...
This movie moved the timeline on by 8 years. The 'set-up' after a few more years could be very different indeed.