1.) Most people are running XT as a vote for bigger blocks and not because they specifically support BIP101. If Core supported bigger blocks, most XT users would switch back to Core and XT would die.

2.) In this high stakes game of poker, XT just went all in, but Core still has the far better hand. There are many, many scaling solutions Core could adopt that would appease XT users enough to kill XT. Don't let perfect be the enemy of good. The real question is whether or not anyone can provide enough Core leadership to reach "consensus". The longer it takes for Core to reach "consensus", the stronger XT gets.

3.) Bitcoin market price has a far greater mining centralizing effect than larger blocks ever will. Right now, miners with reasonably efficient hardware and energy costs (.5W/GH mining hardware, 10 cents per kilowatt hour power, $250 BTC price) spend about half of their mining income on electricity. If the total Bitcoin market cap is under ~5 billion at the next halving in July 2016, it's game over for all but the most efficient (large) miners. The mining centralization that may occur with 8MB blocks in 2016 is nothing compared to the centralization that will occur if the total Bitcoin market cap does not grow substantially between now and the next halving.

4.) Investors hate uncertainty, and the blocksize issue is adding a lot of uncertainty right now, which makes the mining nightmare scenario outlined above more likely. The entire ecosystem needs time to adjust and grow once a Core scaling solution is adopted. Hopefully this issue will be revolved well before the next halving in July 2016 so the market has time to adjust and grow again.

5.) Not-BitcoinXT is a really terrible idea. Mike has proven time and time again that he will not blink or back down. The chances of Not-BitcoinXT gaining 25% of the hashrate are pretty much nil, so in effect, all Not-BitcoinXT will do is help XT reach the 75% threshold sooner and end up putting more people on the losing side of the fork.