However; there will always be some vestiges of Breton culture. People speak a few snippets of the language, and most people know basic phrases like degemer mat for welcome, or that the Breton word for Breton is actually Breizh. These are things that people see on signs, not normally something that's shared among family members though. The actual nuts and bolts of the language are only maintained through songs or in the names of dances, or the occasional song.
This song here, for example, was popular a while back in France. The band, Matmatah, was formed in Brest, the westernmost city in Bretagne. The song itself is Lambe an dro is actually in French, but it has that very Celtic rock edge to it. You can find the lyrics here. If anything, this song actually reminds me a lot of that song "500 Miles" by the Proclaimers or to a lesser extent "Jump Around" by House of Pain. It doesn't have all that much to do with actual Celtic culture, but it's more than happy to borrow from it.
Breton in Brittany is more of a cultural thing now than an actual language. You will see the black and white flag and coat of arms all over the place. Also there's a certain symbol called the triskelion in English, know as la triskell in Brittany. It's the regional symbol, and you will see it everywhere they can stick it up. Originally, it was a sacred symbol, but now, you'll see it on everything from a taxi service to pizza places.
Another interesting thing that I remember seeing long before partner and I moved was a character called Bécassine. It's a stereotypical creation of the old fashioned Breton woman. Her name is also used in French as slang for a fool. She was created as a caricature of Bretons in general, showing her as old fashioned. She still wears a lace coif and clogs, and usually is not drawn with a mouth. She's kind of a classic plouc. It's an old joke, but a lot of people say, "Bécassine; c'est ma cousine." It's actually a song written by Chantal Goya.
The language still exists and there are always attempts to maintain the level of the language, but like any language, it will only stay alive so long as people speak it. I can't say I've ever heard it spoken, but it's amazing to think about how this language has lasted all these years. Of course, like any language, it's changed with the times. For example, most signs are in Breton and French in the Rennes subway system. That's the sign of a language that can stand the test of time honestly. It has to be able to stay current with the times.