According to Bitmain's ads for the S2 kits back when they had them, they stated that both S2 and S2 kits would be upgradable having the ability to swap out the boards with new boards containing the new chips. Based on the fact that Bitmain said the upgrade would bump the S2 up to around 2Th/s and considering the new S3 boards push about 240gh/s(so 10 boards would be around 2.4 th/s), I would put my money on the fact that the upgrade to the S2 will be a hardware upgrade. Also considering the new chips run at around 0.5w per gh/s a stock upgrade probably won't require a PSU grade(although if you want to OC you will probably need to). Anyways those are my thoughts.
i agree with 10 boards, but they will probably underclock the chip, hence 1.8-2th, not 2.4th
Yeah come to think about it they would probably have to underclock the chips. If you go buy what Bitmain posted about their chip specs with a stock chip running at their low speed of 14.18 gh/s using 0.528w/gh and 16 chips per board(if the new boards are the same as the S3 boards just like the S1 was to the S2,mostly) that gives you 160 chips pulling just under 1200w(ps I'm not an electrical engineer so the I could be horribly wrong with my calcs). With that the chips would need to be underclocked in order to run off the 1000w PSU. As for price who knows I am hoping for cheap, but thinking probably around 1.5-2 btc.