Are they really losing sales? Tim Cook makes it sound like they're selling a lot of MBPs and there's nothing to worry about. I don't think shareholders care about butterfly keyboards, they care about the return on their investment and so far apple is till making money hand over fist.
I'd be surprised to apple abandon the butterfly keyboard, if not for the simple reason of pride, its their baby and all they need to do is tweak the design, which we'll no doubt see in generation 4. By dropping the butterfly keyboard outright they'll admit its a failed design and that could open the door to negative PR, especially with legion of 2016/2017/2018 owners now stuck with a failed keyboard design. Instead they'll just tweak it, and like the 3rd generation, they'll not really be too communicative of the changes.
I think your right as all Apple cares about is image & sales. Apple's solution is very clear buy the next model, as my late father would say "fools and their money"...
Q-6