And all you have to do to make them compatible is retrofit 3rd rail shoes and CS equipment. Not that difficult at all. And anyway, PTC will begin to supplant such equipment, making such a crossover easier.
Since they are here for Dual-Purpose shoes, is there a consideration of sharing M8 or M7 equipment between the fleets for "reasons of the future" going on? I'm guessing it would be easier to retrofit new shoes than to lay all new electric rail.