There's trigger_changetarget which, obviously, changes the value of the specified entity's "target" parameter. But the "next stop target" and "target" are two different parameters, so path_corners are not affected by the trigger_changetarget. There are also such entities as func_trackchange and func_trackautochange, but they are not really what you're looking for, and they probably work only with func_tracktrain.
You can try mapping for Sven Co-op, which has a "trigger_changevalue" entity, which is the same as trigger_changetarget, but can change almost any parameter's value.