OK guys, it's over.
As some already pointed out, 2012 was the last time any MBP was upgradeable.
So, how much do you love macOS? That is really the question, and you'll DEFINITELY have to put your money where your mouth is, because Apple WILL NOT reverse course here. EVER. I said it when the Retina MBP first came out, and I'll say it again:
"Apple will remove something you will miss with each iteration."
I also said that Apple's ultimate expression of what a computer should be is the iPad. This is just one more step towards that ultimate goal.
I can't wait to hear the anger when they go all-ARM, and make macOS go away in favor of (a hopefully more capable) iOS.
For my part, as long as the Terminal, filesystem access, and (Android-like) desktop customization is there, I wouldn't object to, say, a Surface Studio-like iMac where the "i" stands for iOS. it might even be fun.
Not for everybody, but enough for me. Until then, my 2011 17", 2012 15", and perhaps a refurb Retina 13 (if I'm desperate) will serve me well (because I can just keep upgrading them).
That is, unless I finally decide to give Windows a try. Their trackpads (in many machines) have improved to the point of parity with the Mac version. That was the last anchor keeping me in the Mac camp.
It saddens me a bit that Apple is going this way, but hey, the future is certainly uncertain. I also hope Google and Microsoft capitalize on all the bad press Apple is getting and pull a "what iDon't Droid does" rabbit out of their hats.