A new rumor says a new iMac will launch in the last quarter of the year with either the latest Intel chipset, Kaby Lake, or AMD’s Zen processor, as well as AMD’s Polaris Graphics set.
My take: we’ll certainly see an updated iMac, probably in October. It won’t pack a Zen processor (powerful, but pricey), but will include a Polaris graphics card. It will pack a Kaby Lake processor — IF they’re available in time in bulk. Right now there’s some question as to whether that will happen. The caveat to this situation is if Apple decides to discontinue the Mac Pro line and offer an “iMac Pro” with a Zen chip, which boasts eight cores and 16 threads
Don’t expect any major design changes to the all-in-one. However, it’s very possible that Apple may offer all Macs with flash drives only, dropping the Fusion drives that have been available in iMacs in the past two years.
Also don't expect an 8K Retina display. On the bright side (pun intended), we may a True Tone display, which uses new four-channel sensors to dynamically adjust the white balance of the display to match the light around you for a more natural and accurate, paper-white viewing experience.