Height slider♥

They can do it but they wont.
The Sims 4 (despite what many say) has provided the highest quality sim content.
Clothes haven't been better (quality wise) and each one individually fitting to a sims unique body type. Its actually fantastic. But with they way things are going its hard to do. TS3 and TS2 had random derps in clothes and their quality.

TS4 now has feminine and masculine frames, good quality sim cosmetics and Toddler, Child, Teen, Young Adult, Adult, Elder life stages.
Height would certainly be hard to do, but its definitely possible in ts4.
They have approaches to it.

Optional is three heights to choose from or a height slider.
An optional three heights could let one simply choose out of three heights but it would very likely require a huge update.
On the other hand they could do a huge morph update and make sliders to lower height for waist and thigh and calf and arms.

I think its possible but probably is not going to happen.