I would think it unlikely that there would not be a T4i(?)/650D before the holiday shopping season this year. I would also think with all Canon's focus on higher-end cameras (5D3, 1DX, and cinema) so far this year, they won't neglect the lower-end all year but could easily bump an xxxD to September. While most of the xxxD have been February/March/April cameras, the Rebel/300D and XTi/400D were September cameras.
I also don't know what Canon might accomplish regarding improvements to the APS-C sensors this cycle (having been focused on FF and cinema sensors), but they have not been afraid in the past to have an xxxD sensor exceed their xxD sensor. I refer to the XTi/400D in September 2006 having 10.1 Mp while the 30D had 8.2 Mp and then again in March 2008 the XSi/450D having 12.2 Mp while the 40D had 10.1 Mp.
It would seen possible a new xxxD might have a Digic V and more in-camera processing features without a major change in sensor, in which case I would expect a significant sensor upgrade in either a 70D or 7D2 late this year or early next after the new xxxD. Once a 70D/7D2 is announced with an improved sensor, then I would expect any subsequent xxxD to have an improved sensor also. The further we get into the year for an APS-C camera announcement, the more likely it will involve an improved sensor.
However, April is not over yet and we may still get a camera announcement -- and don't forget the glass!