I'd happily trade my Mk1 for a Mk2 with the proper dealer involved. But unless the offer is great, the differences are incremental enough I feel no urgent need to do so. The Quantum is a timeless, endless instrument as is, the best synth I have (and that includes the A6). I'm glad to see they're doing a refresh on it. The added memory, poly aftertouch, improved screen.... basically Waldorf is addressing any remaining potential shortcomings of the original, or any issues which have cropped up since its launch.
The extra voices is nice for those who really need it, but I never have; the synth is easily too rich-sounding even with just eight, I'd probably drown in 16!
Ditto the sampling space. For those like Kurt Ader and a few other pro sound designers who make heavy use of the Quantum's sample space, sure, it will be most welcome, but it's certainly not a necessity to the instrument's sonic characteristics. It'll be room for some great sample libraries, for sure, though. It's already easy enough to swap in and out which samples I'd like to have for various purposes with the existing memory size, but it would be one less thing to have to think about on a complex synth.
Those of us on the beta (most Quantum users, I suspect) have already seen what a miraculous job Rolf Woehrmann has been doing evolving the original; this is a testament to Waldorf's commitment to this design.
If you already have an Iridium or Quantum, sure, no worries; this isn't like a Prophet 3 vs. Prophet 2 type situation, but it's a great opportunity for new people to join the community. Congratulations to Waldorf!