If he’s smart he’ll run for the Senate again in 2020. He could win this time, especially if the seat is open. But I suspect he does believe all the hype and will run for President and lose.
Beto would handily defeat Cornyn in 2020, who might decide to “retire” if Beto runs again for the Senate. People in TX believe in Beto for many reasons, including immigrants from CA and NY.