Vote. You don’t have to vote for Biden or Trump, you can write in a vote or choose a third party or independent candidate on the ballot, if your State allows it. Not for the reason of making practical change, because it won’t in a two party system, but to show the analytics, media, the ruling power that you don’t have to vote for the lesser of two evils. Anyone that says otherwise does not know what democracy means and supports a broken system through enabling. Local votes ate more important IMO, always vote for that. The more informed you are, the less likely you are to support a broken system.
Whether he runs again is not the right question. The council for national policy, an extreme right organization, is behind trumpism, supreme court justices trump nominated, and project 2025 which has been around since Reagan era but with different names. They will choose a different candidate as their wrecking ball who is younger and as fiery, unethical, without principles and an “outsider” as trump represent. Whether it’s JD Vance or someone else.