5850 crossfire or hold out for upgrade

Currently I have the following home built system:

Intel i7-930 @ 4.0 GHz
6 GB RAM at 1600 MHz
Sapphire Radeon 5850 (stock... can't unlock voltage)
23" monitor at 1920 x 1080

My question is should I get another 5850 and crossfire the setup or wait for the next generation of offering from NVIDIA and ATI (6xx and 7xxx series, I guess)?

I don't feel like swapping the 5850 for a 6970, or similar, as I feel I could spend less for a second 5850 and get better performance in games that utilize crossfire. On the other hand if I just wait a year I could save the $180 and pick up a card from the next generation which I imagine will rival the power of crossfired 5850s for around $300 or so.

I've Google searched the topic and the questions I've read are to Crossfire/SLI previous gen cards or upgrade to current... hopefully my question is different enough to warrant asking. I'm willing to just use the 5850 on the current settings, which are more than OK for most games, but I could also enjoy higher settings, now, too.

Thank you!