Too many variables involved to figure out if electronics will continue to overheat over time.
So you want to run a power tether? I've seen some high-voltage/low current tethers used for multi-rotors before. But don't know a whole lot about them.
With a tethered power cord, in most cases, you will not be running the peak current of the ESC.
If you choose your ESC with much extra capacity, you should be able to run indefinitely. Regarding the motors, the same idea applies. Use motors that provide significantly more energy than you need and run them at lower capacity.
With those two employed in that manner, the issue then becomes one of bearings. Probably not a issue practically speaking.
What is your application for this vehicle?
I had in mind to create a ground 'moving battery' with a predefined perimeter course with a security drone flying above it.
That sounds interesting.
It would certainly prevent a fly-away!