This just changed Gintama and the rivalry right through its very core. Sorachi's idea of grudge between former comrades is vastly superior compared to other cliche'd shounen series. This is how it's done. I can say with absolute certainty that I will never see Gintoki and the rest of the gang the same way ever again. I mean SWEET BABY JESUS, that was one hell of a chapter.
Sorachi doesn't have to kill a main character to break hearts. This is some next level shit. All those ignorant souls who think Gintama can never pull a seriously dramatic arc with a major twist.. boy do I have news for you.