Canon was miles ahead of everyone else for years with their sensor technology. Their shoice to do it in-house, design their own sensors and processors, to build their own manufacturing lines, and their commitment to using CMOS in DSLRs were all great decisions that put them way out in the lead from around 2000 through around 2007 or 2008. Canon was the leading edge of DSLR tech... everyone else was following their lead. That was a pretty long run as "leader of the pack" in the world of cameras.
Then everyone else copied them, switched to CMOS after they'd taken CCDs as far as they could and were tired of getting skunked by Canon, jumped onto the full frame bandwagon that Canon first proved possible and viable.... Even today, only a few camera makers do it in-house (Sony cameras with Sony sensors). Most still outsource and are dependent upon others for their sensors (example: Nikon using Sony sensors).
You can be certain that Canon has new technology in the works, in the pipeline for future products. There's no way they are simply going to sit on their laurels and let the digital camera market slip away to the competition. Heck, Canon announced a 50MP sensor five or six years ago... It's probably in use in satellites now, or other high end applications. I bet they've come a long way since then.
It isn't so much that Canon has slacked off, just that the others have scratched and scrambled really hard to catch up (to survive, actually) and in some ways have managed to surpass Canon.... right now.
But it's like a game of leapfrog... Expect Canon to one up them sometime in the not-too-distant future.
Keep in mind, as a corportion overall, Canon is one of the biggest players by a huge margin. Sony is really their only rival in scale, the only company that has a similar or slightly larger footprint. Most of the other camera manufacturers don't even come close to these two.
One thing you can be sure... There is no way that Canon will start buying sensors from Sony. It just ain't gonna happen. Canon has no reason to do so, many reasons not to do so since they have their own manufacturing facilities.