I think it's coming, along with MV delay capability. These are two of the more frequently asked for enhancements, and, can be done in s/w without requiring a h/w change (Rachio says it's a s/w company).
I think 16 to 32 zone is hard. I think its order of complexity is similar to moving from a 32 to a 64 bit OS. Version 3 has to keep track of a whole bunch of details, optimize them, and then schedule them.
I think Rachio is late on putting forth an update. I think it's an intentional decision. I think it's a gamble of 'we won't lose market share, even with such incredible delay, because what's coming is incredible enhancement.'
I also think there's no way anyone 'in the know' is permitted to comment here. I think at this point it's 'no comment' (mckynzee uses many more words to say as such, above).
All IMO. We're all just going to have to wait. My bet is that you'll be better off waiting than moving on. (But, I too am about to become a victim in the contest.)