The 1GB of VRAM on those cards is going to hold you back a bit - they really aren't that great for 2560x1440. Where you're not VRAM-limited, your cards will perform slightly below an HD7950. It's a good time for you to upgrade - the current AMD game offerings are great, and no, new cards are not just around the corner. The latest estimate is Q3 2013.
I'd say go for it - you can still sell those cards for a bit of money, making the upgrade less expensive. Of course, you should mention what your CPU is, as that will make a big difference in determining whether it's a worthwhile upgrade.