The question of re-introcing Breton in Brittany could (should) be disputed. In my opinion, Gaulish was never spoken in this area, and there was a linguistic continuum across the "British Channel" (which we call "Breton sea"). Unfortunately, insular Conish was extinct too early..., allowing this theory to become prevalent, against linguistic evidence.
Now, the position of Breton is a difficult one, as pposite to other minor languages in France (Flemish, Alsatian, Catalan, Basque), who all have a strong basis over the border. But it is not desperate: every day I enjoy seeing on the TV (local channel) young children taught in Breton and speaking it as their real mother language... just as 100 years ago their grand-grand fathers were proud to show that their descent was able to speak fluently Frtench, while they could not.
At times, I fear that French could be endangered the same way by English!