I've yet to see any official word that new kit is coming, or even on what direction Meridian intends to take the next generation Sooloos gear, but whispers from dealers etc. suggest that it may be wise to wait a bit before taking the plunge. If you're impatient then you can do what I did: buy a TwinStore (unlikely to be made redundant by whatever comes out next) and start transferring your collection.
I actually went in to a dealer planning to buy a TwinStore and Control:10 but was really unimpressed with the Control:10 after the demo. The software is nice but I found the hardware clunky and inconvenient, and ended up using the iPhone app to pick tunes during my listening sessions. That and rumors about imminent new hardware meant I bought the TwinStore but left the Control:10.
I'd love to see a Control unit that does away with the screen and adds appodising and the ability to play video and multichannel audio. That combined with enhanced functionality in the iPad/iPhone/ iTouch app would be great. I do feel a bit silly having had a fully loaded TwinStore sitting around for the last month, but even if the new kit doesn't offer what I want it should push down prices of current gen Control:10.
Good luck with your choice.
D