Many hours later on the day I discovered my iPhone 6 would not sync with either iTunes OR iPhotos here is the resolution: older iMacs and Macbook Pros need to update from OS X version 10.6.8 (or whichever version you have) to El Capitan. Once you do this, newer versions of iTunes, iMovie, Photos (which replaces iPhoto) and all other apps are then automatically updated. In my case, since I had 'reset' my iPhone this caused me an additional step of having to restore from my last backup; thankfully, that was only 10 days ago. So I only lost 10 days worth of photos and videos. IF I hadn't reset my phone, I don't think I would have lost those 10 days worth of photos.
All of the above was verified after spending 30 minutes on the phone with Apple's Support phone line. The migration of my photos from iPhoto to Photos is still going on and I'm guessing it'll take 1-2 hours.
I'm now able to sync my iPhone 6 with my iMac running El Capitan. There was no cost to upgrade in my case the Mac's iOS and no cost for Apple Support. I had to be given a special code to find El Capitan in the App Store since you can't just search for and find it.