Could RetroArch be ported to Dreamcast?

Yeah right. Homebrew for Dreamcast is anything but dead. It's emulation that's dead on the Dreamcast. Maybe fewer homebrew releases come out compared to 13 years ago, but the ones that do now are much more mature and are from teams who really care about the system, not people who had a passing interest in the hot new thing like it was before.

 

There are more then a few Dreamcast enthusiast community's online, I mod at two of them. I can get a Dreamcast SD card adapter donated to you if you're serious about doing a port.

I'll tell you one thing the gaming press loves underdog stories and the reviewers seem to have a soft spot for Sega's last system, this kind of port would make the gaming news.