You must not know a lot about computers. FIrstly the current setup you have will last for a few more years without even needing to update to a 2080 card in the laptop. That being said when you are ready to add the 2080 it wont be available for your laptop anyway and quite frankly you will probably getting ready to spend way to much on your next over priced laptop.
You will need to be extremely careful with putting the liquid metal on since you have less room for error on a lpatop CPU/GPU.
Future note dell is way overpriced. I love my MSi laptop and currently building a new desktop by comparison most prebuild companies are at least 2x the cost to do it myself. My laptop is an i7 8750 with a 1060 card and I see no reason to upgrade it anytime soon and this is on a 2 years old setup. I did however get IC Diamond paste on it at the beginning of the build and have not had any heat issues.