I don't think the amount of chakra matters in the sage training. Sage training teaches one to utilize an entirely new form of chakra outside themselves, therefore I think it's just important to be good at chakra manipulation. As for the toads, Naruto could have him sign the contract just as Jiraya did for him. I agree with the many other posts here, I think Konohamaru's going to be a pimp when he grows up. He owes it to his grandpa and I think he knows it. With his will and Naruto and the others backing him we should probably expect great things from himyh but konahamaru doesnt have the same amount of chakra that naruto has so he wont learn the sage arts. he doesnt have the toads alliance (which are my fave summons cause they are funny and cooler than an angry hungery snake that threatens you everytime you try to use it) and not very many people can actually learn the rasengan cause of its difficulty. hes still funny though.