I think stem cells could have a big impact not sure about a "cure" but perhaps show a significant slow down. The question could be what kind of stem cells? Fetal, embryonic, adult, stem cells from bone marrow, stem cells from skin they need to explore them all to see which one's are the most effective. Then the next question becomes about the safest and most effective delivery system into the body.
Right now there is no one really saying they are a cure all but they are the best hope out there. There is just a lot of unanswered questions out there that research will hopefully answer.
Also keep in mind, that to my knowledge nothing out that is being explored will revert the damage already done. It is all about protecting the remaining stem cells therefore slowing down progression and then hopefully figuring out how to perhaps stop progression.
One step at a time, unfortunatly with this disease as everyone knows time is precious!