I have a theory that the mythical "Satoshi good end" will be Satoshi accepting that he doesn't love Mary and accepting her and Kendos relationship and as a result Kendo teaches him some stuff and he gets better sexual stamina and ends up with Shizuka. That would basically be: Everyone wins, except Arato.It would be nice to see, but I don't see her following him just for the sex no matter how good it is, since she won't get much else from him and wouldn't even be his main squeeze, that's why Kendo wouldn't bother with her under most circumstances.
I think that's also why Kendo mentioned Satoshi had a better chance, since despite being a weak halfwit, he clearly can met her emotional needs more than Arato... now if only he could last long enough he would be set, lol.