Adopting stepchild

My stepsons mother was diagnosed with end stage liver disease just over a year ago. Does not seem she is a candidate for a transplant, and her health is declining. Without a new liver, I don’t see her surviving. Of course not right away, but in the future if she’s passed away, would I be able to legally adopt my step son?

Edit to Niki: It’s not that there’s no donor available, living donors can donate half their liver. I think it’s not option because of her current state of health, and not changing health behaviors - still drinking and smoking.