The OP's thread title, "45 min layover in DFW: will my bags make it?" poses a question that's impossible to answer. They might, they might not.

My experience with 40-45 minute layovers at DFW is that, most of the time, the bags made the connection. A few times, they didn't.

Are you feeling lucky today?

AA is pretty good about delivering bags if they misconnect. Once, they put my bags in a cab and sent them to my home about 25 miles from the airport.