Wow I'm surprised at the negative feedback in here but I can see where you are coming from, the immortal metaphysical power vampire crap does indeed feel surreal and I'm wondering if the Gorilla pulled this out of his ass or planned it from the very beginning? :D
I don't think that this confirms Sensei being the final boss and Gintama ending in a cliched way but the chances are there :/
Insane chapter with very heavy Star Wars vibes and it just feels so weird getting to know who Sensei truly is...wtf Sorachi.