Indeed. If he gets to go first on that issue tonight, he should extract a pledge from Cruz and Rubio that they will do all within their power do delay any appointment until a new President is elected.
One freeper has already said Trump could end the race tonight by pledging to appoint Ted Cruz to the position.
I don’t believe legally Trump can promise anyone anything until after he wins the nomination.
Not to imply some of the suggestions be viewed as "stunts", but that an announcement as suggested, or Cruz himself asking to be excused and walking off stage ... or any other such action ...
The most watched television event since the invention was invented !