If they do manage to beat Intel on IPC, it's going to be Athlon XP vs Netburst all over again...The 4700x can reach 4.3ghz on one core. So I wouldn't count on 5ghz turbo. Maybe 4.7ghz. I mean it will be close, but TMSC process and amd's architecture isn't there yet.
Though if they do finally be able to pull off a push in IPC, it won't matter, if a 4.7ghz single core will be just as good as inte'ls 5ghz, considering intel kinda stuck in the same IPC for years.