Think of stem cells are building blocks. They can be red (skeletal), yellow (neural), blue(heart tissue), green (liver) -- whatever color we would like to make them.
What needs to be determined is how do we stack those blocks so that e.g. a blind man can see again. A stroke victim can regain use of their body again, etc. We can create the cells. But just implanting them in a damaged area and hoping everything will connect properly is fantasy, not unlike taking a bunch of computer components, throwing them in a shoebox and having it magically become an Imac.
It could potentially cure anything that requires cellular replacement.