I don't know about formal research, but there's definitely a track history of membrane keyboards and other such "advances" that kill the physical feedback becoming miserable market failures. Given Apple's usual attention to detail about the importance of such tactile feedback, I can't imagine them going to a system that rejects it. Moreover, we're not seeing non-Apple PC vendors moving in that direction too, even though it's hardly expensive or technically difficult these days.
To the extend that tactile feedback is important for efficient typing, I imagine keyboard design for laptops is a tradeoff between good feel, durability, and making the mechanism as lightweight and shallow as possible. I'm typing this on a recent-model Thinkpad, and the key throw is about 2mm, substantially less than a high-feedback clicky-key type keyboard.
I have a MacBook 12". It took me either months or more than a year to notice that the haptic touchpad does not depress at all when you click. It happened suddenly when I pushed it while the laptop was powered off, and I panicked, thinking the pad was broken / stuck.
I still grin like an idiot pushing into the pad and telling myself that no, my finger did not go down. It is really magical.
If this can be done behind an eink screen or something similar, with a distinct feel for resting a finger and pushing a button, I believe it can be day and night for laptop keyboards. Alternatively, these eink screens could for sure have ridges for key delimitation.
To the extend that tactile feedback is important for efficient typing, I imagine keyboard design for laptops is a tradeoff between good feel, durability, and making the mechanism as lightweight and shallow as possible. I'm typing this on a recent-model Thinkpad, and the key throw is about 2mm, substantially less than a high-feedback clicky-key type keyboard.