IOTL Maximilian and Mary had three children Philip the Fair, Margaret and Francis (who didn't live long). When Mary the Rich died she was only 25 years old and she and Maximilian also appeared to have had a good Royal marriage.
In other words more children seem to have been likely.
Plus Mary the Rich will finally fulfill her father's ambition, she'll be queen of the Romans (consort) and later Holy Roman Empress (consort). OTOH a final peace treaty with France could be a bit more difficult ITTL.