I'd create a DLC where you could work as part of a VTC in single player. The companies would vary in terms of cargo specifics ie construction only (Materials and equipment like diggers) to a "we transport it all" type.
In this the player would also be able to manage their own company to a greater depth than what we have now, again working as general cargo or specific cargo and have options to manage each driver to "only pick this job type" based upon their skills when you hire them.
If you want to train them in other areas, they have to go through training which puts them out of action for earning, whilst you're still paying them a wage per day/week. The same can be said for training the drivers so they can haul different types of gases/ liquids.
Finally I'd expand the paint customisation aspect in ETS2 so the player can have greater control over their paint jobs and have the ability in game to create their VLC brand. You want that cool paint job DLC that you got for your cab on your trailer? Go for it. Want to put the dragon at the back of your trailer so it looks like the flames are being aimed at the cab? You can do that too. Want to add custom text somewhere? We have that also.
Guess that's more of an overhaul than a DLC but.. that's my idea
