Based on recent news, there will be ways to do more than just SLI (and go to 3 or 4-way.)
Also, count me in for a hydro copper. Using a custom loop at the moment and getting a card with a block is going to be important for me. Debating getting one early though and just running it on air until I get a block to install or just waiting and buying the preinstalled one.
(Have 2x 680 4GB Classy with the coveted 680 Hydro Copper blocks at the moment, so should be a decent jump!)