"the Kids don’t necessarily need to fulfill the Masterpiece and go after Caliborn" So, the ending of the Credits snaps means more that he's done with Caliborn completely, rather than "okay i'm coming to beat your ass"?

Honestly, it never sounded like “i’ll do it” in the sense of “i’m coming to smack you up bro”, it really just seemed like him saying “i’ll break my phone dude, stop talking to me!”

I mean, first of all, the Caliborn teasing John is not even the Caliborn from the Masterpiece, because he doesn’t have the Ring. So straight away, they wouldn’t be warping to beat this Caliborn’s ass, or Caliborn’s ass in that moment. But second- Look at the rest. John is kind of depressed and needs something to do, and I could see him going ALONE to beat Caliborn’s Ass. But, Rose being lovingly married to Kanaya and helping with the Mother Grub? Roxy, Callie and Jane being happy together? Karkat and Dave being boyfriends with the potential Poly Jade? Dirk and Jake ambiguously reconciled and sparring together and making fun robots?

Unless there’s a solid reason for them to go back and risk their lives, it’s going to take more than John Egbert wanting to slap Caliborn’s face to get them to do it. I’m not saying they’re not going to go after him later, when some time passes and something happens, but definitely not right after the Credits.