from my understanding after killing it off, sega pretty much opensourced all the code to make games for it and basically said 'pirate away we don't care'.
If you were to find a dreamcast, I'm pretty sure you could find a working copy online that you could just burn to a cd and play.
Double check first tho, I only vagualy remember reading that somewhere online so I could be wrong. I never had a dreamcast, so the perticulars never stuck.