Certainly, that's how they get your money. Offer a new feature as "Pro" feature for a generation or two, to entice people to pay more. And then make it standard across all models later.
Personally, I'm not the type who cares that much about 120Hz, it doesn't make a difference to the user experience for me. So it's really a "Pro" feature in that Pros are the only ones that care about it, but having Always On could be interesting.
These days.....Pro is the most abuse term in Appleland. It just means "top of the line" and if you approach Apple's offerings with that in mind, there is no confusion about why it's called "Pro"