The future of Bitcoin is bright either way, BUcoin HF or not. I'm using every possibility to increase my Bitcoin stash, the cheaper the better!
My doubt is if splitting the miners with the competing chain could expose core to significant risks of attack for a while. There would be even some lagging until difficulty adjusts. But probably nothing of dramatic.
Depends on how many miners switch. Imagine 50/50. We would have double the blocktimes for 2014 blocks? (Depending of course when the HF starts)