One would think there would have to be a Canon 7D replacement, if there is none, then there will be mighty big gap between a $1000 T4i* and a $3500 5DM3. Canon seems smarter than that to me.
The same thing is happening at Nikon, the D300s is due for a replacement, if there is none then there is a big gap between D7000 at $1200 and the D800 at $3000. There are rumors that the D400 is full frame or is going to have 24MP, who knows, no real info as of yet.
Both companies need to have a flag ship crop sensor body this time around, maybe next time they will be lesser full frame bodies.