We know that Mexico's status or shape when the Mex Am war is basically... poor, in a very bad shape, So what if Mexico is basically Economically and Politically Stable, The economy on good shape, The military on good shape. Maybe after indepedence things went more smoothly than IOTL, How would it affect the war and everything if that war still happens at the same date iotl the only difference is Mexico is on good shape.