At least one of the chankast authors (I don't really know about the others) is working on another project. He prefers to spend his (probably little) free time on that project, so let him have fun. Use google and you'll probably find who and what is he working on.
If they decide to update chankast or release the source, is up to them but:
a) Dreamcast are cheap, really cheap, and it's better than any emulator (until it breaks, of course)
b) As a coder, I'd rather start an emulator from zero than just wait for a source release. So if there are people interested on emulating the DC, they might be working/reading about/whatever now.
And, remember, emulation is about preserving and documenting the machine specs, not making happy the warez kiddies.