The difficulty is set to double in a few more days. Then after the next block, if you don't upgrade to a high-powered third generation DX11/GL4 GPU, it's going to be slim pickings for GPU miners.
The future of mining is with FPGA clusters. There's some guys who work at security firms who have huge clusters for breaking weak crypto who are turning them into bitcoin mining centers. We're talking like 100 or more terahashes/sec per FPGA rack.