ProMods

Would be great if we could include the Tunel du Aragnouet-Bielsa with its difficult climbs from the French side and stunning views. Sadly I am just a novice with editing maps and would like to do it with one or more persons

yeah it can be really interresting. I just hope it's not too near the Somport tunnel.

I don't think so.
It's about half way between Somport and Andorra.
I've actually been there and it is quite interesting.

Somport is roughly 200km further west, more to the Jaca region. The Bielsa-Aragnouet (D929,D173,A-134) route practically starts at Lannemanzan exit on the Autoroute A63 and ends at the A-23 at Barbastro (between Lleida and Huesca).
The fun thing is that the Bielsa route takes you over steep climbs deep into the Pyrenees in the Vallée d'Aure (1000m increase in 19km) to the tunnel entrance located at 1800m, going through tiny french and spanish towns. That's why I think this extra cross-border tunnel would make a lot of fun and sense with truckers going from Toulouse to Huesca or Lleida and possibly even Madrid in game. The tunnel itself has an incline of 5,1%

Another note: I think this border crossing has unusual kind of signs, correct me if I am wrong; but I drive 15 years now in total to Spain, only saw this one at Bielsa-Aragnouet
Bienvenidos a España
France 1Km

5.1% uphill that's a lot for trucks

Trucks are not banned in this tunnel but the traffic light from the image is designed to trucks. The tunnel is very narrow and the truck must wait for the traffic light to turn green, so that people who come from the other side will stop.
I think this could fit but I'd consider the N-230 near Vielha is more important than a first-level autonomic road (A-138 in this case).

CptCaribbean, on that I do agree.

Totally true, but the thing is that this route is challenging for trucks, which is in my opinion a lot of fun. The incline towards the tunnel is 10% on the french side and is 5.1% in the tunnel. In real life snow chains are compulsory in winter. It used to be a Route National, now its a departamental route but still the road is used for 10% of total traffic by trucks, which I find a lot for a road with these caracteristics.

Is the Spain / Portugal region the next 2020 DLC that will be developped by SCS ? Or they will focus on rebuilding some older parts of the map ?

Nobody knows that yet.