The Stern gang, who killed him, became the IDF (along with the Haganah and the Irgun). These groups performed the ethnic cleansing of Palestine that allowed Israel to be built on Palestinian land (commonly known as the Nakba). > One of the chief organisers of the assassination was Yitzhak Shamir, who became Israel’s prime minister in 1984. Exactly.
The Irgun was forcibly integrated into the IDF, claiming dead and almost triggering a civil war. Something the Palestinians could never muster, and one of the reasons they are still in this position, stateless under the control of Hamas
There was never a consensus on the Oslo accords from both sides. While the Israeli Labor pushed for the process, the Likud and the rest of right wingers worked thoroughly to undermine it. And on the Palestinian side, the OLP, essentially Fatah, went on to accept terms every other Palestinian faction refused to adhere to (demilitarized state, practically land-locked on a mozaic of patches that amounts to a fraction of the country's total area and surrounded everywhere with ever-increasing Israeli settlement projects.
That effectively weakened Fatah's position which essentially morphed into a caretaker on behalf of the Israelis for the day-to-day. And the resistance weight shifted from secular factions to the Hamas.