If I were Apple, I would replace the entire bottom part with a touchscreen, I suspect it is what they are moving towards too - not very comfortable to use, but it would at least have a use for people like me who almost never uses the keyboards, could be entirely configurable, view data when the keyboard is not being used
Mechanical keyboards all have their issues, for me, the fun is to overcome those issues, fix the issues when they arise, rebuild when it's not possible, but for a non-serviceable laptop, I think the less mechanical the keyboard the better
Tho, as Daniel pointed out, a seriously hefty laptop with serviceability would be nice too, kind of like a small desktop with a lithium battery attached - at least it's what I dream of on the opposite side of the spectrum