I agree, win10 is quite a bit faster than Yosemite, I haven't tested El Capitan enough to say either way other than boot.
Boot times (Tested on battery):
Acer V7 latptop (4720hq/16GB/256GB mSata SSD) - about 10s power button to login (UEFI)
Elitebook 850 (4600u/16GB/256GB Samsung 840 pro SSD) - about 10-12s power button to login (UEFI)
2015 rMBP (4870HQ I think/16GB/PCIE insane SSD w/El Capitan) - about 12-13s power button to login
I haven't had a chance to play around much inside El Capitan, but I think the best it could do is just match windows 10 speed. As others have said here, W10 runs insanely good even on really old hardware and non-ssd systems. They've done a great job, couldn't have done much better in my opinion.
Apple will be fine and continue to cater. The majority of people that buy their products want all the fancy integration between the iphone/ipad/mac....call hand offs, messaging, airdrop, and many other mac only ecosystem features, and the best trackpad on the market (still).
I love both platforms really, I really like seeing the competition and love using both OS at the moment.