well.. the new problem is throttling which might be much severe and yet we still don't know how effective this will be.
No, Apple said that this keyboard is only available for 2018 models since they shaved the upper case a bit and probably this won't fit well for 2016 and 2017 models.
In that case, I guess Apple is prepared to buy back the 2016 and 2017 models for 70-80% of what customers paid for them. People pay Apple's prices expecting to be treated right. It's totally unacceptable that the 2016 and 2017 laptops are lemons, and that they expect customers to continuously bring them in for repairs.