The difficulty here is butterflies. You haven't just changed 1960 and onward, or even 1947 and onward when Jack went into the House. Papa Joe was having an effect before that. He was big in the Stock Market (exploiting every loophole) and was investing in films, and that's where he made his money. So you affect that. And he had his own political career before his comments on democracy being finished in England ended it. The appeasement criticisms would continue to taunt the Kennedy family. It was one of the reasons John F. Kennedy was worried about disengaging overt support from Vietnam (being called an appeaser) and when Kennedy was assassinated, you'll notice a man with a black umbrella in the background, which was a guy using an already then archaic taunt of the black umbrella of Neville Chamberlain. Anyway, you affect those things listed, as well as Boston politics.
And also note what becomes of Rose Fitzgerald (later known as Rose Kennedy). The Fitzgerald's were an established political family, notably with "Honeyfitz" Fitzgerald (Rose's father). It doesn't matter with Joe Kennedy or no Joe, they were already established. So who she then marries affects local politics, and potentially state and national politics, and of course you have the effects from a lack of a Kennedy clan.
The effects really depend on what comes from want of a nail. History and a point of departure more specifically is like a pinball: you shoot it off in a direction, and it would keep going that direction if unimpeded, but of course it will be because you have all the obstacles that it'll bounce off of. That initial shooting is the POD, and the obstacles are the things thereafter and all the chance and different possibilities that come and affect history. And the problem being we don't know a lot of those obstacles, and even if we did they aren't going to definitely be one shape. Rose Kennedy could marry such and such a person, but there's also the prospect she could marry this other person, and both possibilities are legitimate given you've opened up infinite possibility with an alternate history scenario. Things get complex.