Yes, years.
It's not really a matter of the capabilities of the drones themselves, but other practicalities.
If you want to replace TV camera bikes, you've got to replace all of them, all of the time
The main objection is this sort of thing:
View: https://www.youtube.com/watch?v=xeviAWB0i4Y
(drone nearly landing on Marcel Hirschi).
That's the reason why, in the UK at least, flying a drone over the peloton would be illegal, and that the drone operator has to remain in sight of his drone at all times (under a vehicle roof would be unlikely to qualify).
Where do you put the drone pilots?
If it's in an open top car, you're just replacing motos by cars, which, whilst they may largely avoid drafting, are going to cause even more problems with safety when they try to get past riders, or wait to be passed by riders.
Flying to one side of the road has the problem of roadside trees, which would constrain the drone to the road (to say nothing about the affect on the sight lines of the drone operators trying to remain in sight of their drones).
Drones at CX races (and MTB):
Those I've seen have, apart from pre-race course previews, been cable cams rather than drones - i.e. cameras suspended on a system of overhead cables, cable car fashion. The give away is that you get the same moving overhead shots every lap, and occasionally you can see the shadows of the system..