I think that at least Serial and Sound(wrapped PortAudio soundsystem+plugin/wav)
should go into plugin or core packages, since they are fundamentals.
Serial code won't change in the future, and probably neither PortAudio,
so maintaining code is not an issue, copy/paste packages to core would be fine.

If one is eager for upphub thing, then one could probably create converter
from bazaar to upphub, and mark/review packages as fullyFuncional or unmaintained, etc.