1. Mile Pence (2025-29)
2. Beto O'Rourke (2029-37)
3. Ben Shapiro (2037-45)
4. Dan Crenshaw (2045-49)
5. Alexandria Ocasio Cortes (2049-57)
Or
1. Kamala Harris (2021-29)
2. John Bel Edwards (2029-33)
3. Ron DeSantis (2033-41)
4. Elise Stefanik (2041-45)
5. Alexandria Ocasio Cortes (2045-53)
AOC would almost surely be 2028 nominee vs. Pence if establishment Democrats still haven't broken through after 3 terms.
Beto will almost surely be old news 10 years from now if he's not already the VP. He needs to either win outright or get VP in 2020, or win TX-GOV in 2022 and then win outright in 2024.
I think that 2028 is a bit early for AOC to win the Democratic nomination, as she will only be in her late 30s by then.