From my prediction about Forrest Gump ITTL, he's still going to school after her mother makes out with the principal, then meets Jenny for the first time in the school bus, interact with Elvis Presley during his stay at their family inn in Greenbow, Alabama and show him how that dance originate and became his signature style later, and Gump finally broke his leg braces after beginning to run fast towards their home.
Then in the 60's, he's still going to be an iconic college football player that later became part of the All-American Football League and meet President JFK in The White House. With JFK survive ITTL, Gump will not yet going to serve in Vietnam like IOTL (or both with Cambodia ITTL) until later between 1969-1970 ITTL and discharged by 1975 ITTL. Throughout the 60's ITTL, Gump would still be graduated from college, then likely joined and became part of different causes of the decade from Civil Rights Movement, Second-Wave Feminism, Hippie Movement, Woodstock Music Festival, and New Frontier Democrats. He could meet and interact with Martin Luther King, Marilyn Monroe, VP Terry Sanford, and RFK. Gump and Jenny will meet again on these occasions that I've mentioned like in Washington D.C. IOTL, including the Black Panther Party. Forrest and Jenny would vote for JFK in 1964 ITTL and became Democrats after he won the election.
In the 70's ITTL, I'm assuming that Gump would be drafted to Cambodia ITTL and still meet Bubba and Dan like IOTL. He's still going to be awarded The Medal of Honor, this time by President Romney ITTL for saving the lives of his army troops that includes his late friend Bubba. While recovering from his injury, he became a professional ping-pong athlete and played in China during his visit there just like IOTL, meet with President Bush ITTL for being the leading athlete of the team, then interviewed by Dick Cavett with The Beatles ITTL on the show, and finally meeting Dan again in New York like IOTL. I don't know if you're going to involve him in The Manson Capture, The Hoover Affair, The Assassination of President Romney, Doe v. Bolton, and Equal Rights Amendment in this movie but I'll let you decide. After his military discharge, he's back home and start the shrimping business that Bubba promised until Dan shows up that he made promise to him back in New York to help make this business and made them multimillionaires. Still, her mother dies from Cancer, invested early in Apple Computer IOTL (now Xerox ITTL) to help improved the town he's living, Jenny will arrived at his family inn, but I'm hoping that she finally accepts his marriage proposal earlier ITTL, Dan would show up to the occasion with his new metal legs and his wife, then having their son that we knew as Jr., spend the time as a family, until Jenny passed away in her sleep from AIDS, and buried her from the same tree that they became friends like IOTL. Or maybe she gets her treatment to battle AIDS now with President Udall passing the bill for Universal Healthcare Act for all Americans, she can be one of the survivors from the disease and later became an advocate if she'll live beyond the 80's ITTL.
I think they'll support and vote for Udall in 1976 and RFK in 1980 with them being a major part of The Boomer Generation (born between 1946-1964) thanks to JFK ITTL being their president that they can relate, inspire, and support to with him alive ITTL. I proposed that Gump would be an advocate for the better treatment of the veterans who served in Cambodia ITTL, then maybe the leading figure of this movement. I don't know if you're still going to include the scene where he runs across the US like IOTL, but I'll also let you decide as well. This would likely happen in the 80's ITTL.
That's my prediction for the plot of this movie now that everything changes ITTL genius. The film is still going to be nominated and won all of them in The Academy Awards later in 1995. I'm also looking forward if they're going to do a sequel after that about what's going to happen with them throughout the 80's and the 90's ITTL, but was later scrapped after 9/11 happened IOTL. Without 9/11 ITTL, it's possible that they're going to make the sequel. The sequel novel is going to be a lot different ITTL Mr. President, and I'll be gladly to watch this movie version as well ITTL.