I wonder how soon these nav units will be available to buy for reasonable money in the aftermarket - plenty of ebay suppliers for new RNS510 around £300 (light fingered VAG/Blaupunkt employees?).
Chances are that the new system will be standard equipment for a good number of years, seeing as the MK5 and 6 Golf, as well as all the other VAG models over the last 8 or 9 years have been fitted with the RNS510.
Wouldn't be surprised to see a standalone Discover Pro for self fitting on the net for £500-600 in the not too distant future - at that price I might be tempted, plus you can whip it out and reinstall in your next VAG or sell it on - much more residual proof.
I found a new standard discover nav system for MK7 Golf on ebay the other day but I can't find it now (it was from an international seller and the naming of it would make it hard to find, I stumbled on it by accident) - it was £370.