Mahito is one masterfully crafted character, he was made for us to hate, his ability his looks his origin all of it there too make hating him all the sweeter. When Yuuji finally exorcises the shit of this fucker it will cathartic.
But... truth be told only a death like that to kill a character like Nanamin, he just too good for anything less, and the author roped us in thinking that since he survived the first times against Mahito he would be always here, he only killed enough characters in the past to give a false sense of security then punched us with this arc.
There is so much still not in play, Yuuta, the third years ( one of them recognized by Gojo), people from Kyoto, the true identity of the false Getou, Sukuna interest in Megumi even why Megumi sister is in a coma ( heavily implied to be a mass curse ) and this arc just upped the stakes.
I really want Maki to be alive.