I work in an ASP and can throw in there, for what it's worth (as others have mentioned), that the part number for the 2017/2016 MBP top cases are the same, so if you have a 2016 MBP and you have this issue, at least, you'll be getting a 2017 top case. If you have a 2017 model, well...
Anecdotally, we haven't yet had a 2017 model come in with a keyboard issue. We also haven't had a MacBook come in for a while, so I could be wrong, but I think the top case for this guy is only the same for the 2016/2017, leaving the first-ten 2015 out of luck. Frankly, the first-gen MacBook is the most finicky out of the bunch.
There is actually a stop-gap measure before an entire top-case replacement, and that's to replace the keycap in question. However, if that doesn't work, or if the mechanism breaks, there's no choice but a top case replacement.
I honestly wonder if this might be the most costly repair program for Apple, followed by the "Staingate" LCDs. Replacing the LCD (clamshell) may not be that costly from Apple's perspective, but they designed themselves into a corner where the top case is concerned. The top case is pretty much the whole computer except the display (clamshell), logic board, and bottom case (the cover). So the top case includes the battery, keyboard, the trackpad, (taptic engine), speakers, and the touch bar/touch ID (on touch bar models). This may be 1/2 to 1/4 of the machine's cost.
You can't reuse batteries after you unglue them (safety concern), and even if you salvage all the other parts of the top case, how much time does it take to unfasten and fasten a new keyboard, with its hundreds of tiny, single use screws? It might be faster just to assemble a new shell and keyboard from scratch. But again, the problem is all these components that are glued down to the top case—namely the touch bar.
I highly doubt, at least for now, that those with 2016/2017 models will continue to only get 2017 top cases. I think there is a 2018 top case in the works that will be compatible with the 2016/2017 models and will eventually flow into the repair channel after the 2018 models are released. So, a rev 3. The way they're designed, the top case and the logic board are the most costly components of the Mac, so to have a replacement program that constantly replaces them with the same flaw doesn't seem financially viable to me.
As others have mentioned, this might also be why we haven't seen any 2018 models yet. However, 2018 models are almost a certainty IMO, given that most PCs are just now launching with the 8th Gen Intel processors. Quad-core processors on a 12" laptop? 6-core, i9 processors on a 14"+ laptop? PCs this year are going to leave Macs behind in the dust if they don't move to the newer Intel CPUs by the end of the year.