Keeping it optional indefinitely, then, defeats this goal.
I don't see how this thing is practical across the entire Mac line.
1. Widespread touchbar adoption
2. Increased sales of Apple keyboardsActually, I do: They'll raise the price of the cheapest iMac configuration and include the keyboard in the box. After seeing the starting Mac Mini prices, it makes total sense.
I only estimated that they were going for 100% laptop coverage. But I can imagine a future where Apple keyboards have a touch bar option. Though not as important because Macbook touch bar penetration can drive developers to integrate with it, alone.
At which point it's not much different than gestures when it comes to answering your questions. What happens when you use a Logitech mouse on your macOS desktop instead of a Magic Trackpad?
Note that touch bar integration cannot have unique features, so it's never required. The challenge is to get developers to care about it which is the prerequisite for users to care about it.
Having seen teardowns of a MacBook, I'm pretty sure that one without a touchbar would be more-or-less a completely different computer - different keyboard, yes. To accomplish that, though, you'd need to also make a different housing to accommodate it, and a different motherboard, too, because this stuff's all soldered together as a single unit these days.
And for all that, people would still be griping about the keyboard and the monoport.
They ignored those for the 2018 MBP refresh, probably because the new Macbook Air was coming. I'd bet on the full keyboard MBP getting discontinued now that it's out, or best case having the 2017 hang around while the touchbar models continue to see updates.
The Escape has higher powered CPUs than the Air or MacBook, but I don't think anyone is buying from those three based on horsepower.