I haven't heard of anything big coming from creative in the near future other than a pci-e x1 version of the x-fi they showed off at ces. I'm not even sure if that one is scheduled for release or was just a prototype.
I wouldn't worry too much about it though. Sound cards aren't evolving at the same speeds most of the other pc components are.
A 4-5 year old sound card like the SB Live! series is still good enough for most people even today (although apparently not for vista.) They aren't like video cards which in a year or 2 they are pretty much made obsolete.
I'm sure if you invested in an x-fi it would probably last you longer than the rest of your pc.