I don't think Canon will lose their #1 status next year, but if they do I believe it'll be Nikon will take that spot. And if that does happen, I think Canon in the latter months of 2012 will come out with something that'll bump them up in the pecking order again, ending 2012 #1. Just my 2 cents
That all depends on how far they fall behind. If Sony/Nikon come out with a real winner in the first half of the year, Canon could find themselves under a lot of pressure to sell anything to new customers in the second half of the year.
NEX does not replace a dslr or worry Canon at all.
I think quotes like that are a worry. If I'm doing street photography, why wouldn't I prefer a NEX over a *SLR if the IQ is comparable? Smaller, less obvious/intrusive rig. Similarly if I can pack a NEX into my backpack rather than a heavy *SLR for landscape work, why wouldn't I want to save on the lbs on my back? NEX has a lot to offer...
DxO Mark rates the NEX-7's APS-C sensor at 81. The 7D scores 66 and the 5D Mark II scores 79.
Whilst the difference between the 5D Mark II and the NEX-7 is too small to notice, what this means is that moving to 24MP on APS-C will not cause a drop in IQ and if you move from the 7D to the NEX-7, you not only gain MP but you gain IQ too. The NEX-7 score is 25 to 30% better than the Canon 7D. Additionally, going to the NEX-7 from the 5D Mark II gets you 3 extra MP and no loss in IQ. Only if you need shallow DoF does the 5D MarkII make for a compelling buy.
Whilst the NEX-7/SLT-A77 do not have the AF capability of the 7D, for anyone that doesn't need that AF capability, Sony's offerings is very very compelling.