As for Intel chips, I was referring to Broadwell in spring 2015 and Skylake in autumn 2015. Broadwell is the tick (new process, 14nm) and Skylake is the tock (new architecture on 14nm process). The way I understand it, Intel had problems getting the new 14nm process up and running, and so the Broadwell chips were delayed until spring 2015, and that pushes them up against the Skylake release in autumn 2015, which Intel has said they are still planning on for a release date for Skylake even with the delay of Broadwell. So I'm planning on a Skylake Mac upgrade late next year.
You're referring to Intel's line of mainstream Core i5/i7 desktop chips, in which case you are accurate. However, the Mac Pro uses the server line of Xeon chips, which is traditionally one-step behind in architecture. The Mac Pro uses Ivy Bridge-EP right now. Haswell-EP chips came out last month. Broadwell-EP won't be out until late next year, and Skylake-EP in 2016. The only reason Haswell i7s and Haswell-EP has lined up this year is because Intel is delayed on Broadwell, which should have had desktop-class i7s out by now.
All of that being said, all of the parts for a potential Mac Pro refresh are out. New AMD FirePro GPUs have replaced what the Mac Pro cards are based off of. Haswell-EP is out (and OEMs like Apple have likely had them for some time). DDR4 RAM is available to consumers. The pieces are in place, Apple could in theory release one next week.