The catenary is no problem. You just don't erect the poles and wires until you're ready to go electric. The bigger problem is the waste involved in building a ROW suitable for 200 mph running and then never running anything faster than 90 or so.
Also, I think for security reasons, when you have an overhead crossing the rail has to be on top and the road underneath. If the road is on top it just makes it too easy for a drunken high-school student to pitch a concrete block onto the tracks. Although I admit that 60 feet in the air may be over-egging the pudding.