It wouldn't make sense to give the 70D the old sensor. That would mean the 70D would be stuck with obsolete technology until 2015. That's just ridiculous and I hope Canon is smart enough to know that.
the XXD line is for enthusiasts and semi-pros and those buyers are savvy enough to know when they're getting garbage. I think to compete with the D7100 Canon has to bring its new sensor with improved dynamic range and noise performance in the 70D, have AFMA, 100% viewfinder, at least 6fps, and built in wi-fi.
I can also hope for 1080p 60p video, built in timelapse and hdr modes, better weather sealing, and a 2x crop mode like the D7100.