This idea is strengthened by Jamie Foxx having previously said that unlike how his character was depicted in The Amazing Spider-Man 2, his Electro in Spider-Man 3 will not be blue.
Let’s also not forget that although J.K. Simmons briefly reprised J. Jonah Jameson last year in Spider-Man: Far From Home, it was the MCU’s Jameson operating The Daily Bugle as a controversial news website, as opposed to the Jameson we saw in the Sam Raimi-helmed Spider-Man movies.
As such, unless there’s a resurrection in store (which, to be fair, is commonplace in superhero stories), it’s possible that Alfred Molina will appear in Spider-Man 3 not as the exact same Doctor Octopus we saw in Spider-Man 2, but a similar version of the same character from either the main MCU reality or another universe.