RousseauX
Donor
I don't think they've got much of a choice.They either innovate themselves,open to western ideas or die.Without the northern regions,they are back to being in the same situation as the Song again,having a chronic shortage of horses and cavalry.The only alternative would be to arm themselves heavily with firearms and even then,it wouldn't guarantee success given as you mentioned,firearms ain't the magic bullet against nomads until the 18th century.
Firearms aren't the problem, the Ming used firearms extensively