Okay, I'll bite. Let's see. I must say,
@flemishcap has it pretty solid. Though I will change some.... actually I won't. It seems pretty realistic.

The only question I have is if they will actually ever do Belarus. If not, just remove it from the list but keep everything else the same. It would just be weird to not have them on the map though.
1. The Balkans Coratia, Bosnia blah blah blah, etc
2. Redone Benelux region.
3. Greece/Albania/North Macedonia, etc
4. Redone "Going East!" expansion
5. Belarus
6. Ukraine / (Maybe split into two DLCs?)
7. Redone United Kingdom
8. Ireland/N. Ireland
9. To The North Pole! (Northern Finland, Sweden, Norway)
As for the Balearic Islands, it would be similar to how they added islands with the Italy DLC. That makes sense, but not a high priority. Maybe send some rookie designers to do those as their practice.
I personally think the bus thing will be a new game, not an expansion. It will just be based on the same map and world as ETS2.
I agree with
@Silverwing on what ETS3 would be.