you don't have to wait if you don't want to, you won't get a better card then a 7970 for AWHILE so it's definitely worth the investment if you want a top end performing card. kepler will use the same 28nm manufacturing process so it's not like it's going to be leaps and bound better then AMD. not like how ivybridge with its 22nm process is going to absolutely kill AMD in every aspect
IMO it's the main reason AMD is getting out of the CPU business and focusing on APU and GPU's. they simply cant compete with intel beyond this point since they don't own their manufacturing plant like intel does.
It would be interesting if intel ever decides to beef up their GPU division and start competing in the APU market. I've seen some very promising (and disturbing) previews on how well the ivybridge's IGP performs, if it can perform like that and still be a cool running chip, then AMD may have to totally rethink what markets they can compete in.