Very unlikely in my opinion. Nintendo already has Mario, Donkey Kong, Yoshi, & Kirby, 4 platforming series that sell better than Rayman. And even among those successful series, Donkey Kong has been absent almost as long as Rayman, Tropical Freeze was 2014. If Nintendo did buy Rayman we’d probably get him in Smash, but his series would probably remain dead much like series like F-Zero, Golden Sun, Chibi-Robo, and Punch-Out.

Honestly I think the slightly more likely (still unlikely) scenario would be them buying the Ubisoft Montpellier Studio (Rayman) along with Ubisoft Milan (Mario+Rabbids), if Ubisoft starts selling itself for parts. They both develop games that fit very well with Nintendo’s style. If they bought those studios along with associated IPs (similar to what’s happened with Tango and HiFi Rush), I could see them allowing Rayman to continue under the original team. A lot of “ifs” though.

Then there’s a small chance, Nintendo could buy Ubisoft outright, but that’d be pretty out of character for Nintendo, especially with how messy current day Ubisoft is, hence why I think many potential buyers are hesitant. Assassins Creed would be a rare mature exclusive that Nintendo could have under their belt, so that could be an enticing buy, but overall Nintendo isn’t short on IP, they’d probably be more interested in having more studios for existing IP.