So i'm 100 % sure Engineers had a thought about this, but now that  LTE  is getting pretty Standard worldwide for phones, why not make a Drone and a Remote Controller that both uses a SIM-Card to communicate wich each other? This would provide an unlimited flight distance, since both parties would have an Internet connection and a P2P Server to use.
(And since LTE can go up to 250 Mbit/s, Bandwidth would be sufficient.)

Of course the Batteries won't allow that until we get hours worth of battery lifetime, but i always thought that would be so awesome

Take a look at Andruav for android. it works pretty well and uses  3DR flight controllers and a telemetry module to communicate vai x2 android phones. Its fine for mission updates on things like RC planes but FPV on a quad? I think the lag would be to much.

It's a good idea but in order to have unlimited flight distance you have to have unlimited battery life too.... In my opinion it's better to have 2x much battery life than to have 2x distance flight.

https://www.qualcomm.com/news/re ... celerate-wide-scale

Only problem is if the cell signal switches towers it may not always communicate.  Plus most laws anywhere are line of sight to your drone.

With the range on the Mavic, the battery is going to be the limiting factor.

If you want long range FPV, look at powered gliders with UHF TX. There's guys going out to 40km plus.

Do you really want to put the trust of your expensive aircraft in the hands of your mobile phone carrier? I know I wouldn't.

The additional practical concerns with this are due to taking up channels across multiple cell towers.