Just introduce advanced modulation options like NI Massive's/Spire's performer or the multiple modulation targets. Virus is already falling behind modern synths in terms of versatility. Just search around other forums and listen to what your users say.
No-one is going to be paying 2k for a synth that is behind in ANY factor than a 150$ synth. Give more MODERN tools to your users, more envelopes were a step in the right direction. Modulation should be next, add performers and give us a clean semi modular approach to modulation targets and sources. The matrix is not bad by any means but it cannot be compared to the power of massive.
Update your wavetables with some more modern ones. Maybe add a couple of classic oscillators close to what sylenth offers in terms of sound quality. It is sad to have weaker classic osc on my 2.2k euro synth than the ones found in a 150 euro one and having to resort to cheap tricks by using the hypersaw to alleviate that.. Come on its 2013...