Jacks already wants the club to fall. That was made apparent when he stabbed that dude instead of taking him alive to roll on Hale. He's gonna read the letters that the Irish chick left for him and he's gonna catch a glimpse of Gemma and Clay's little secret concerning John Teller, which is almost certainly that John tried to disband the club as well, and they (or possibly just Clay) killed him to save it.
Jacks might kill Clay and possibly even Gemma. He'll probably let Jimmy get away to South America thereby letting that part of his deal with Stahl fall through leaving the club to take the full hit and do a good stint of time as well as screwing Clay's deal with the Irish, effectively cutting off the Sons' main source of income. They're already having issues pulling in people to cover for them while they're inside. Coupled with the incorporation of the police department, Sam Cro is a house of cards, and Jacks just has to sneeze to bring it all tumbling down.