If you put Yuan into the Northern Wei mode, probably she would either be another Tang, with the size of land and population covered, and the booming trade of Silk Road as another successful dynasty that served by many would-be famous Confucian scholar-officials; but, like Northern Wei, some factions in the court might well be displeased by the corruption the sedentary culture of China brought to the nomadic Mongolians, and even lost their original culture(that was why the Manchurians still maintained their customs and even forced Han to assimilate to a certain degree), and may even start a war that torn the country apart, as we had Western and Eastern Wei from Northern Wei, but this time might be a Northern Yuan in North China, and Southern Yuan in Southern China, conveniently separated by the Yangtze like the Sixteen Kingdoms era.
But, if there were able emperors managed to separate the Han and Mongolians enough such that Chinese culture was tolerated and Mongolian culture was maintained, then you got Qing mode. It would bring more political stability than the previous mode, as it would not risk to lose their own culture, the conservatives might likely willing to compromise, but they may find it unnecessary to assimilate the Han to Mongolian custom like the Qing example, as the histories of Liao and Jin showed possibility of ruling non-Han and Han successfully and prosper, they might build a structure similar to the two states, which had Mongolians and Han ruled by two administrations, a quasi-confederation of two nations under one dynasty. And of course, she would still prosper.
And of course, the eventual flood of Yellow River would came in, but since the assimilation would have the large Han population found no need to rebel, a rebellion came from it was nearly impossible. She would well be joining the unity-diversity cycle of history.