This is exactly why this current era sucks so badly and seems to be a no win situation.
How I see this conundrum progressing: Let's say Apple releases five new computers in 2017 and they all flop. But they flop strictly because they're genuinely just bad, underpowered, non-upgradeable, etc. Apple will interpret the lack of sales as confirmation that no one wants a computer anymore. They won't realize it's because they released regressed inferior machines that people don't want, and especially for the cost of multiple thousands of dollars.
Like the quote above says, lack of sales will only be seen as proof of changing markets and that personal computers are dead. We'd like to think that lack of sales would cause them to reflect and re-evaluate what they're producing. Unfortunately, I don't think Apple would see it that way.
If we apply the same measure to the Windows PC world, that example fails miserably. Since the decline of the desktop PC year after year must mean people are not interested in cheaper more powerful computers. They fail to see the decline is due to mobile computing and not needing more powerful desktops for the majority of people. Microsoft & Nokia dismissed that trend, and now one company has disappeared in to obscurity.