Other than Ainu and the languages of the Ryukyu Islands (
Okinawa, etc), the languages in "mainland" Japan are regarded "dialects."
Many share much in common with "standard" (Tokyo-speak) Japanese. Some, like those in Tohoku (northeastern) region, appear to be far more remote in linguistic relationship. Still, most of them are thriving in their respective regions.
However, I feel these dialects are slowly fusing together with advances in telecommunications (TV and other media) and travel. A lot of dialects enjoy exposure on TV media, and a lot of people who presently live in the Tokyo area are originally from other parts of Japan. Although they pick Tokyo-speak, intonation and accents of regional dialects are seeping in. There is also the strong presence of the Osaka dialects (Kansai-ben) that is affecting Tokyo-speak in idomatic phrases, accentuation, etc.
The Okinawan language has also become "fashionable" among young people today, that Okinawan words and phrases have also entered the standard vocabulary.
The Ainu language is dead, with the last speaker of the language having passed away a decade or so ago (according to a TV documentary I've seen). There are people of Ainu ancestry but they already have mixed with the general Japanese population.
HTH!