Other than Rayman Legends, I had that same feeling since 2011. Welcome to the club.
The Mario + Rabbids games aside, I feel like the last game that Ubisoft made that had a shred of passion behind it, was probably For Honor, but that game is super niche, and really wasn't my thing (and has since been morphed into another Live Service). Other than that, probably the Rayman games, as you say.
Who would even buy them or their IPs at this point? EA, or that one company that bought all of the Western Square Enix AAA games?
I always underestimate how big THQ Nordic's pockets apparently are, so it is a possibility. I would probably rule out Microsoft, Sony, or EA. I would actually guess that a company like Amazon or maybe even Disney would be very interested, though.
The IPs aside, I do genuinely feel like Ubisoft has value within it. The global infrastructure that they have created is immense, and no doubt there is at least some creativity within their many walls. With the right leadership, they are more than likely capable of creating something decent.
But I definitely don't see Ubisoft succeeding if they stay their current course.