This map shows a way I would reorganize the Basque Country:
The resulting division is composed by the French Department of Atlantic Pyrenees in blue on the map (Département des Pyrénées-Atlantiques) - the remaining part of what is today the Department of Atlantic Pyrenees will be renamed to Department of Gaves (Département des Gaves) - and by the two Spanish provinces of Pamplona (green) and Bilbao (purple). The three capital cities of the three subdivisions, which are respectively Saint Sébastien (well, I guess the French will franchise the name), Pamplona and Bilbao, are colored with a darker shade of the said color.
To make these divisions I based on geographical borders: the thicker red line is the European continental divide; on one side there’s the basin of the Ebro River which ends in the Mediterranean Sea, on the other side there are the Atlantic Ocean’s rivers basins, part of these sub-borders are shown with red thiner lines. Many of the municipal boundaries don’t match exactly those red lines so minor changes should be made (just in the international border proximity) but I decided not to show them here.
The lighter shade of blue indicates the area once belonged to the Kingdom of Navarre on the northern side of Basque Mounts, for this, it can be called “Transmountain Navarre” while the rest could be called “Cismountain Navarre” (meaning respectively and literarily Navarre on the other side of the mountains and Navarre on this side of the mountains).
The lighter shade of green is what Bilbao gains, Bilbao absorbs entirely the Province of Vitoria, the Treviño enclave, the valley of Deva River and the municipality of Valle de Mena, this province also lose to the Province of Santander five municipalities to the west that you can see in light brown on the map, this last change together with the previous two are made to make both northeast and northwest Bilbao limits geographical.
Thick yellow lines delimit the area where the Basque language is spoken by the majority of the people while thin yellow lines delimit the area where the Basque language is spoken by a plurality.
I guess that now I owe you some explanations for the title, well, the Basque people is now even more divided than before and if that wasn’t enough their core is no more on the Spanish side but on the French one and France is one of the worst countries (and I’m being polite) in terms of linguistic minorities protection. So yes, the Basques are pretty f*cked now
Now now, as you can see I broke any linguistic, political, historical, traditional, cultural and any other type of border to only care for the geographic ones, I think that this is going to shock more than on person
PS: Yes, I just gave a huge amount of land to France, one can argue that the are better possible geographical borders between Spain and France but the point is that to the Northeast the Basque Country border lay on a hilly zone where it is hard to find well defined geographic elements, in the center and to the West on the other hand the territory is more mountainous so that geographical lines are more easy to find.
2xPS: I would like to add this to this map
but I don’t if I should modify that directly or update a new version, please vote below