I think President Kennedy would have won re-election in 1964, I have no doubt about that had he lived. I think we would have had Civil Rights and that Civil Rights would have gone pretty much as it did in OTL.
The big difference I think would have been Viet Nam. Had Kennedy lived I don't think we would have gotten as heavily involved in Viet Nam and/or as bogged down there as we did under Lyndon Johnson. There is even some realistic speculation that had Kennedy lived we would have significantly reduced American combat forces in Viet Nam, perhaps that American combat troops might have even been pulled out altogether.
I feel if Kennedy had lived he would have been easily re-elected in 64, everything else would have gone pretty much as in OTL except for Viet Nam, and under Kennedy Viet Nam would have been very different.