I wouldn't expect significant price reductions in the 570 for some time. Even if they do go down it wouldn't be by enough to be a game changer for your build.
The new intel CPUs that were just released target the very high end and offer virtually no gaming performance above a 2500k overclocked.
New cards should be released sometime in Q1 2012 (or maybe late this quarter for AMD), but there's always the possibility of delays and scant availability in the opening months. There's always something else just around the corner- I'd go with your build as planned. It will still be an EXTREMELY fast rig for years.