Back in the day, when there was a discussion that followed the retirement of the Evolver, Mopho, and Tetra, it was my understanding that DSI left the market behind, these units had been manufactured for. I think Robot Heart even confirmed this at some point in alignment with a statement Dave often made in interviews, namely that competing with bigger companies in the lower cost market doesn't make much sense for DSI.
In fact, DSI haven't released any derivatives in a long time as measured by the frequency of their annually announced new instruments. The last one was the Mopho SE in October 2013 (the year that is rather remembered for the Prophet 12), which has also been retired by now. Before that came the still available Mopho x4 in August 2012, the Mopho Keyboard in May 2010, the Tetra in August 2009, and the Mopho module in August 2008. The only exception to that fading pattern has really been the AS-1, which happened as a collaborative effort under the banner of Pioneer, though. The latter is also a kind of confirmation of the shifted competitive situation referred to above.
So I would strongly assume that the focus will rather be on new or different designs in the future, apart from the desktop module tradition that we've seen continued in the case of the Prophet 12, the Prophet-6, the OB-6, and the Rev2.