A quicker way than the other solutions currently here: Select the drone hub that you want to assign from Click "Dismantle drone" - this will turn the drone into a drone prefab.
Repeat until you've disassembled the number of drones that you want to move.
Select the drone hub that you want to assign to.
Click "Construct drone" to recreate all of your disassembled drones.
gaming.stackexchange.com/users/126840/Symmetric
As of 19.03.2018 - No, there is no way to mass-assign drones.
Manuel Clicking is required.
Sadly there is still not even a mod for it.
100 is a rather huge amount.
But when I get around ~10'ish my favorite way to assign them is this: Pause game Select Rocket.
Click drone assign to quickbar repeat
2~4
till all drones are on the bar Go to Dronehub use quickbar to select drone assign to hub remove from quickbar repeat 7~9 till done
I believe this list shows that this is a serious flaw and will hopefully be fixed soon.
gaming.stackexchange.com/users/87226/Shaeldon
Left click on drone hub, RC drone, or Rocket.
All drones assigned to it will be shown.
Left click on the drone you want to reassign.
Right click on hub, RC drone, or Rocket
you want them assigned to.
Depending on drone slot availability, it will be reassigned.. Quick.
gaming.stackexchange.com/users/208538/Dimitris
A very simple trick I just discovered is the following:
Land the Rocket filled with drones near a Drone Hub Wait for the drones to leave the Rocket and idle Launch the Rocket back to Earth after it fully refuels This should auto-assign all drones to the nearest Drone Hub.
Hope this helps!
gaming.stackexchange.com/users/208794/Erik Wickenhöfer
I've noticed that you can just launch the rocket and all the drones will be spread among drone hubs in range.
Then from drone hubs the easiest way to reassign is to deconstruct drones at one hub and reconstructing them at another.
gaming.stackexchange.com/users/208904/Fobio24
Finally, here is my fastest method.
For each drone: Add a hub to quick bar Click drone Click "Assign" Right click on the Hub in the bar
gaming.stackexchange.com/users/138930/Galabyca
Let's say I ordered from Earth 100 drones and I want to dispatch all of them through many different Drone Hubs. Do I have to click on each of them and reassign one by one individually? Is there a way to reassign drones in batch or automatically?
Is there a way to reassign drones in batch or automatically?
gaming.stackexchange.com
<surviving-mars>
gaming.stackexchange.com/questions/329408
gaming.stackexchange.com/users/138930/Galabyca
There is no way to mass-assign drones. Manual clicking is required. You can select the drone hub that you want to assign from Click "Dismantle drone" - this will turn the drone into a drone prefab. There is no way to mass assign drones like that. However there are a number of workarounds, for example if you fill a rocket with drones, it may auto assign them to the nearest hub or selecting the drone hub you want, and clicking Dismantle Drone 
Users suggest there is no way to do this. There are a couple of work arounds suggested however.