The original speaker should not really matter. As long as the speaker wires still end at the holes in the wall, you should be able to install any other speaker. If it has a proprietary connector, it smells a lot like the shenanigans that Bose pulls. But you could still rip off the connector and install generic speaker connectors so you could still install your own speaker system with the existing wiring. Thankfully Bose hasn't yet invented patented wiring that only works with Bose speakers. At least to my knowledge.
