Laptop overheating can be an easy fix, what make?
HDD replacement is super easy, same with PSU (unless internal connections are dead).
I've had to re-thermal paste my laptop god knows how many times (seems to dry out much faster than with a desktop).
I did see a mITX case which had a fold out 1080p screen actually. Like a PC/laptop hybrid.
Isn't it super expensive though? (think I know which you are talking about).