It's not like ARP is still making and selling Odysseys.
No, but Korg is, having bought the rights, schematics, IP, etc., no?
Behringer (MUSICGROUP) owns the trademark for a few years now.
Trademarks expire after some period of non-use. I'd guess Korg tried to TM it but Behringer's application beat them to it... and now that Behringer is actually bringing it to market, they would be in a position to insist that Korg stop using the name, or license use of the name from them. If they hadn't brought it to market within a specified period of time--2 years, maybe?--Korg would have had the right to claim it for themselves. You're not allowed to hold trademarks without using them, and there's only so much of a grace period.