Is there a possibility that Trump could launch an independent campaign as a write-in candidate if he was swindled out of the nomination at the last second?
His supporters would back him and if he ran a write-in campaign he wouldn't have to worry about ballot access per se. He is also a household name that everyone knows and even if someone missed a letter spelling it voter intent would still be clear.
Is there something I'm missing?
Many states have deadlines by which you must submit an official declaration that you are accepting write in votes, or else they don't count. Some may be after the convention, I don't know.