May i also say that kakashi will actually decline not improve that is what kakashi fans do not get whenever they say kakashi will get stronger. Im certain ive already proved to you that once you activate the ms you start to go blind whether you use it more often or not, but in kakashi's case since he uses it as a last resort, it will take longer. But regardless he would go blind eventually. In that state he loses kamui, but also the advantages the sharingan gives him, so in actual fact he will get weaker rather than stronger when blindness takes away his 1 sharingan. Also currently in order to be in the big league you need something unique about you, the only thing unique about kakashi is kamui. The other techniques he copies gives him vast knowledge but they are basic techniques, nothing unique about them to further make him strong
While I agree with everything else you've said in this topic, I disagree with this.
I don't know if Kakashi will ever get much stronger than he is at this current point, but I doubt he goes on a rapid decline, because I think, as he's shown now, he will not use kamui unless he or his teammates are about to die, which I think will keep his vision well through his "prime". He's shown since the Pain Rapes Konoha arc, he's trained vigorously to improve his stamina, in order to allow him to use everything other than his mangekyou sharingan to fight with.
He's strictly relying on his ninjutsu and intelligence to win fights now, as he showed vs Deva and Asura, when he had the fight won using just those before backup arrived.
Kakashi is far too intelligent to let himself go blind quickly by spamming the MS.
