The guy already knew and mastered CoO to a very high level in the Skypiea arc and you tell me he won't learn and master other Haki ?
Ok then keep believing that , but don't come shocked when he turns to have became super powerful if he came back.
And no Luffy don't get foddersized by Admiral , he get beaten yes but they not easily.
Ever considered the possibility that Enel could have learnt to use Mantra (Kenbonshoku Haki) before he ate the Goro Goro no Mi?
He has something called the God complex.
is an unshakable belief characterized by consistently inflated feelings of personal ability, privilege, or infallibility. A person with a god complex may refuse to admit the possibility of their error or failure, even in the face of complex or intractable problems or difficult or impossible tasks, or may regard personal opinions as unquestionably correct. The individual may disregard the rules of society and require special consideration or privileges.
Do you really think he would listen to anybody saying he can get stronger? Or Saying he could be defeated by more people than that blue sea rubber bloke? He would kill anyone who talks about his strength as if it was insufficient.
Even if he does SOMEHOW learn the basics of Busoshoku haki : there isn't anybody on the moon of which can compare in strength : nobody to push him to improve his haki or to practice his haki , if he holds back i.e. doesn't kill every ****ing person on the moon : then he won't be improving or learning Busoshoku haki.
Even if he knows the basics. It took Luffy 18 months to get to where he is. An Admirals haki is maybe twice as strong. Twice. Enel didn't have and still hasn't had 36 months , Luffy also had the best teacher and the best conditions.
Enel has: no teacher , crappy conditions , God complex : he won't want to become more powerful as he already sees himself as omnipotent.
And you tell me Luffy never got fodderized!?
-One shotted by Borsalino (whom was being lazy)
-Easily defeated by Kuzan who wasn't even trying(whom just woke up , was tired)
-Would've been one shotted by Sakuzaki if it wasn't for Ace,Jinbe,Marco,Whitebeard who saved his silly ass
Even now after the time skip he is nowhere near strong enough:
Luffy=Law
Law shat himself when Fujitora tested his strength
Law is getting pwned by Doflamingo whom isn't even Admiral tier.
Enel will never be Admiral tier , even if he does ; the Yonkou would still fodderize him as they fodderize admiral tier characters.