Bitwig 5.0 is out! I was looking at this demo of new live performance features and I was wondering… What is missing on the Play to be able to behave like the Novation Launchpad on the video.
Hardware-wise the Play has everything featured there: pads that can be activated with different colors and a shift button. 
Imagine you could use the Play’s audio sequencer combined with Bitwig’s (or whatever DAW) clip launcher using the MIDI mode (i.e. having all the long melodic samples and sequenced soft synths over there).
A Bitwig controller script would still be needed but that part should be doable if the right MIDI data can be sent by the Play, given the amount of controllers Bitwig and the community (well, mostly Moss) has developed.