Well, since Audacity still has very very limited MIDI support, my idea is probably for the very very future warp-time development 
, but… The good old Sound Forge had an incredible function: you could set and link markers/regions (i.e. labels in Audacity) with MIDI notes and use a midi controller (physical device or Virtual MIDI Piano Keybord) to play that labeled audio. This could easily turn Audacity into a very powerful sampler. Also could be very useful if Audacity can record what user plays.
Yes it probably is 