But if this were the case, time is running out for Canon to either produce or buy a better sensor!
It's indeed interesting - and one way out of the dilemma that they cannot compete with Sony's sensor tech nor milk their 18mp for an unlimited amount of time is to introduce an entry full frame body, as it's often speculated.
If time is running out for Canon, it's very slowly: about 2/3 of dslr users I see running around in Berlin are using a Canon Rebel, then 1/3 Nikon and some cheaper Sony, apart from one or two rich 5d amateurs. In the entry segment, Canon is a well-known brand, has its distribution and marketing set up nicely. And in the higher segment, people are stuck to Canon because they've got EF lenses.