Another change, and a very good change, might be far fewer or no Presidential "libraries".
For our foreign friends, each president whether good, bad, or ugly now gets money from the government and benefactors to set up a "library" containing their papers after their term of office. It's an entirely sycophantic and corrupt practice with presidents grubbing about for donations while still in office.
There's always varying attempts to make excuses for this exercise in the personality cult the presidency has devolved into. The "libraries" are often referred to as research centers, a few are actually part of universities, most include a museum of some sort, and most ex-presidents maintain their publicly funded offices there. Despite all the window dressing the practice is nothing more than another method to curry favor with and get favors from presidents.
Garfield, believe it or not, has one of the first presidential libraries. In his case, his widow set up a few rooms as a memorial to him and accepted private donations to maintain the collection. (IIRC, it's now maintained by the government.) While his library was created for a different purpose and in a far less corrupt manner than the libraries that followed, Garfield's presidential library set the precedent. While all of his immediate predecessors didn't follow that precedent, by the 20th Century each president was accepting donations and offers while still in office with regards to maintaining their "legacy".
No Garfield assassination, no young grieving widow, and maybe, just maybe, presidential papers end up in the Library of Congress where they belong after each presidency.