This paragraph is the one that sticks out for me;
Current sales aren’t an indicator of future sales. Apple shouldn’t use the (presumably) low sales of the current Mac Pro to justify discontinuing the line entirely. The 2013 Mac Pro was introduced with a substantial price increase, far less internal expansion, fewer and more expensive processor options, and a forced dual-workstation-GPU configuration even for buyers who would’ve been fine with a single GPU. Then it was abandoned for three years, during which 5K displays finally came to market, but without a good option for Mac Pro buyers.
The 2013 Mac Pro was a victim of limited configuration options in a market that values versatility and edge-case handling, poor timing behind the 5K transition, and years-long neglect. A 2017 Mac Pro need not suffer from the same issues, and could sell far better.