I looked at the future primaries, including today's primary in Illinois. Below are those likely to give most, if not all, their delegates to Romney:
Illinois 69 delegates
Wisconsin 42
Maryland 37
Washington DC 19
New York 95
Connecticut 28
Rhode Island 19
Delaware 17
California 172
New Jersey 50
Total 548 delegates.
Add these to Romney's 516 and you get 1,064. To clinch the nomination, he needs 1,144 delegates. Thus, by the time the convention begins, Mittens will be 80 delegates short of the nomination. I don't think your nightmare is going to come true. However, there may well be a floor fight. I see Romney as the eventual nominee, but with only luke-warm support from a good chunk of the GOP.