Elon Musk has played himself in Iron Man 3, The Simpsons, and in a slightly modified form on Rick and Morty--so between that and his sense of humor, he's got a chance, and I'm looking forward to it. As to Miley Cyrus:
I can see her being in at least one or two, but they've got a strong female cast this year, so that could go either way. My predictions is that they'll push it a little after the monologue once, and once more after Update, but there will be some safe sketches as well.
Specifically, there will be one about billionaires who don't want to run for President, and and on