I still think through all the competition, Canon will remain #1
It depends on how you define being #1. If we're talking about overall sales numbers I think it will be hard for Nikon to rapidly match or surpass Canon unless something seriously drastic happens. If we're talking about leading the industry through innovation while remaining profitable / growing I think Nikon is currently ahead of Canon for the following reasons...
1. Nikon has been announcing products and delivering them on time while Canon hasn't done.
2. Canon's price points have surpassed Nikon's for new releases (1DX vs D4, 5DIII vs D800).
3. Nikon typically doesn't handicap their cameras as badly by limiting their features... for example Nikon provides full color metering for ALL of their SLR camera bodies (and have for a very very long time), Nikon provides uncompressed video output via HDMI, Nikon has provided professional AF in multiple bodies for a long time (Canon didn't until the 5D3), Nikon provides spot metering based on selected AF point for ALL of their SLR camera bodies, etc. The only argument to this that I can think of would be battery grips boosting max continuous shooting FPS (which I agree is lame).
We all know that healthy competition will only benefit us (the users) and hopefully Canon will respond.