Audacity uses PortAudio. The next PortAudio release
(V19) includes
JACK support, so Audacity should work with JACK then. But, no one
is making any predictions about when that will be.
You can build the current release of Audacity from source with
PortAudio V19 as an option. Testing of Audacity with native ALSA
and/or JACK is something that the Audacity developers are looking for
feedback on, as it's a new feature.
Cheers
Daniel