fade from one camera view to another (not change position of camera!)

Is it possible to fade out from one camera while fading in to another camera without interpolating camera positions (which is what set view target with blend does)? I just want to cross fade between the viewports of different cameras; should be easy, but can’t seem to find a way to do it? While we’re at it, can we also cross-fade between two different level squences that are playing? Or a level sequencer and a cinecamera?