Assuming the shooter did not make his called shot in the process, then it is loss of inning only and incoming player accepts balls in position. BIH results from fouls and simply sinking an opponent's ball is not itself a foul if the shot is otherwise legal.
The situation you describe comes up regularly. It is not at all unusual to hit a legal shot to purposely make an opponent's ball (for instance, when it is hanging) to replace it with your own, or to clear that pocket for your balls and/or to take away an easy shot that your opponent might also use to play position or easily break up a problem cluster.
This is true of both BCAPL and WPA (BCA) rules.