So I'll start the thread by saying...... BaBye!!
Now, after you've bought all your Nikon gears and, surprise, surprise, it's not what you thought it was and Canon doesn't look half bad, then you can state your "I'm switching to - Sony....no - Panasonic...... no - well, how about Olympus or....damn it, I'll see if Canon will have me back.
Uhm, not true. I bought Nikon for better AF and it delivered. Now to get that AF again in a new body, I have to buy way more camera than I can handle (physically - I shoot one handed 99% of the time and the full-sized body of the D4 makes that tough). If the 5D3 can deliver what Nikon does in the AF department, I'll come back to Canon.
It's a camera. You buy the one that fits your needs the best. I'm not going to let brand loyalty get in the way of logic.