I don’t know.
Checking around, both Confederate and Bimota are still up and running. Bimota did “die” for a while a few years ago, but was bought and restarted. They’re still making the Tesi, now the “Tesi 3D”, and they even have a spinoff company called Vyrus that also (and exclusively) makes a hub-steered motorcycle. Confederate slowed down during the recession, but still operates, and even moved to a bigger facility not too long ago. They only build 2 models, and only a total of about 30 motorcycles a year, but since they’re not parts-bin specials, I’d say they still count as “boutique” builders.