Anyone that wants to run in this election should try to get nominated by the Democrats, but once the Democratic nominee is set up that should be it. There is virtually no way a third-party candidate could come into this election and secure enough votes to win. Which is ironic because if it was anyone other than Trump, this would be the year a third-party potentially could have won, but Trump has too many staunch voters that would not vote for a third-party so you would only be taking Democrat votes.