Hmmm... I see a lot of complaicency here.
Would not want to see Canon sit back on its laurels from overconficence, nor steam full speed into the ice field (pick your own metaphor here).
First of all, McDonalds (I think) sells more hamburgers than any other hamburger-selling outfit, yet the quality is not generally considered to be that great.
Second, Canon's lead is narrowing and the others are gaining unless I am confused by some detail here, or by the definition of "camera" being used in this statistic or something. I recall market share numbers in the high 40% range a couple of years ago, not the high 20% range.
I think you are msising the point with your McDonald's analogy. Who says the food is not high quality? I agree it's not, but do you have objective data indicating that it is of lesser quality than Wendy's? No, but McDonald's continues (or has in the past at least) to sell more than Wendy's or BK let's say, so obviously there is SOMETHING about McDonald's that is driving the majority of fast food eaters there instead of the other places. You're absolutely right, higher sales doesn't mean better, but it also doesn't mean that it's NOT better either, without substantiated facts to support. The same thing with this silly Canon vs. Nikon. Everyone keeps saying that higher sales doesn't necessarily reflect higher quality. Fine. But can you show me data and statistics to support that Canon's higher sales AREN'T due to superior product? Nobody has done that yet. And they don't owe me that, or owe me anything for that matter. But there is certainly a reason WHY Canon is able to dominate advertising, dominate the web, etc., etc. while Nikon cannot and therefore cannot sell more than Canon.
I will not say Canon produces a better product because I don't know that. But I have never seen two photos and been able to go, "Oh wow! That one was shot with a D800E and the other was shot with a 5D Mark III!" If Nikon had the position Canon did in the sales department, everyone here arguing against Canon would then suddenly use that as a starting point for a claim that Nikon produces better product. It's already been done on here when Canon had an inferior quarter.
Canon makes just as good of cameras as Nikon. They just happen to sell more of them than Nikon.