9th Gate! Gate of Plot! OPEN!
Nah because at this point 8 gates is a joke (not in terms of power but how nardo saved gai life :/) also if I'm not mistaken it crippled gai so I mean I only see lee doing that if nardo and sauce and potentially orochimaru cannot fix what ever problem that required him to go 8 gates
I'd rather lee create new techniques while in 6 gates or make it so he can maintain it for long periods of time I mean the dude unlike gai does not use up any chakra what's so ever maybe if he learned to do that forehead seal like tsusnde and use the chakra stored up to do the gates and have it for long time within battle similar to the release form of tsusnde the only prob with that is is that Sakura would be able to use it ... I'm not ok with that she needs to do something of her own instead of being carbon copy of her master (same with lee but at least lee has good back story for why he replicates gai so much)