I have a mid-2010 (5,1) cMP, 6-core 3.33GHz primarily for video editing. When the nMP was announced in 2013, I decided to upgrade my cMP with more RAM and SSDs (both as boot and an array on PCIe card), plus a new video card ... rather than plunk down my cash on a radical new v1 of the nMP. My timetable for a new machine: Whenever my cMP starts acting up or if it begins choking on 4K video. So far, it remains stable and powerful enough for me to work productively.
But I'm far less tied to the Mac than I was before Apple trashed Final Cut Pro 7 and transformed it into FCP X (don't get me wrong, I know some folks love FCP X and do great work with it). At that point, we switched all our work to Adobe Creative Cloud (was already deep into Photoshop and After Effects, and switching to Premiere Pro from FCP 7 was a breeze). Other than the OS, we run no mission-critical Apple-only software ... and AFAIK, Adobe CC works fine under Windows (please advise if you know otherwise).
So if Apple provides an updated, improved nMP that I can tailor to my needs by the time I need something new, great. But even if that's the case, I'll have to take a hard look at non-Mac boxes, especially if the future of the MP still looks iffy at that point.
In sum, Apple's apparent disregard for the MP (and Macs in general) has transformed me from an enthused Mac evangelist, responsible for dozens of Mac purchases by my business, family and friends over the years, into a definite skeptic. I'm not ready to jump ship just yet, but I'm making sure I know where the lifeboats are.