"Bernie for President" would look great on your bumper.
He already had his chance and he failed.
Look. Even cats have nine lives.
Hindsight is a wonderful thing. The Dems obviously considered that Trump was a grave threat and that the seasoned and well credentialed (but deeply unpopular) Crooked Hillary was the best option to take him on.
Despite polling showing that Trump vs. Hillary = Trump wins, and Trump vs. Bernie = Bernie wins.
Unfortunately the way that Bernie was "bumped" left a bad taste in the mouths of a lot of Bernie's supporters. And I'm sure that was a huge factor in the outcome of that election.
We don't know what would have happened. Perhaps decades of anti-socialist propaganda would have counted against old Bernie in the end.
Running a geriatric socialist against a geriatric and corrupt billionaire at the next election? I would love that. But I can't see it happening.