ChristiaanJ, there is another little detail you may not have thought of. Communications does not have to be via satellite if an alternate link can be established. That greatly reduces the demand on satellite communications. An extended cell phone technology could handle large cells from the air. If the plane is too low and falls out of the large dedicated to aircraft cells you use regular cell phone towers. Only if they fail you fall back on satellite linkages.
Of course, who is going to pay for the development of the large communications cells when no worldwide frequency allocation exists for this purpose; and, getting it will likely be a more than one decade process given how often the international frequency allocation body meets.
It's all an expensive non-starter. It can be done. It'd he fun doing it. It'd be full of interesting challenges. And it would never "pay for itself".
{^_^}