The live stream is mostly easy since you can just use wireless cameras and relay the stream from a computer on the ground. Do you know anything about making the remote computer-based control actually work and also not crash? I haven't flown RC airplanes in some years, have things advanced this far? The military remote computer controlled stuff required some pretty fancy engineering.
Instead, the plane's owner would be responsible for taking over whenever necessary to keep the plane from crashing.
As for scalability, I think collaborative control might be fun, particularly if your influence varies based on your skill level.
If you don't want to ask anyone in particular, you can ask yourself other feasibility questions like: -how heavy will it be? will it affect the flight of the plane? -how much do current planes cost? how does that compare to the cost of adding a camera device? -how many people fly planes? how many planes do they have? -how often do people crash planes, and why do they crash? how expensive is it to fix? how does this cost compare to a camera that could prevent a crash?
my initial guess is that there is no feasible business model there, but what if you twist your idea around a bit? such as sharing videos of airplane flights? and modifying video equipment so that it could be installed on model airplanes? that could potentially be useful.
The idea here is to allow people to profit from their hobby by letting thousands of people fly their planes.
And those people can do so from the comfort of their homes at their computers.
You might have a free service where people fly a plane together in a collaborative way. If you want more control over the plane, then you will need to pay. You might be able to fly for free if you can demonstrate that your flying skills will draw a large audience.
A computer would take over whenever the flight inputs become unreasonable/unsafe.
You could reward people with reasonable flight inputs by giving them more control over flight inputs.
Moreover, the owners of such planes can take over flight inputs whenever they are not safe. It's their planes after all.