I think it would be a little strange to add an entirely different kind of synthesis at this point – but I could definitely see some different modes being added to expand the Digitone concept.
I would dream of …
- 3OP mode with one operator having phase distortion
- Simplified 2OP mode with expanded polyphony
- Drum synth mode (without needing sound locks)
And since a lot of people are asking for VA, one could consider a VA-like mode which uses FM to achieve analog-style timbres. With FM (Phase Modulation) you can achieve quite complex analog waveforms, including actual PWM. 