I don't think hardware analogy synthesizers are going anywhere anytime soon. Moog is probably facing a lot of competition though, and they aren't very active in the Eurorack modular space where a lot of the interesting new stuff is happening. (In particular, a lot of their popular synths, including recently released ones, are being cloned by Behringer.)
It would be interesting to know if they were doing great but sold because the offer was too good to turn down, or if they were in a financially precarious position and looking for an exit.
Not sure what the situation is for the employee's union. If a company gets acquired, does the union remain?