Popping in from March... Previa's a really different deal than a low-lying placenta. I have a low-lying, and am going to have to get its position checked again later on, but my understanding is that a true previa doesn't move off the cervix and a VBAC is not an option. I hope I'm wrong, but I don't think it's likely for her.
On the upside, at least it's a situation where it will be a necessary c/s, and though there'll be disappointment and loss of that hope, it's not the kind of situation where afterwards you have regrets and think, "Oh, but what if I would have..." That's a completely appropriate use of a c/s. Sorry for your friend though for sure.