What's most likely to happen:

1. She'll ask for a raise.

2. She won't get a raise.

3. She'll move to a new company.

Depending on the company point 2 might not look like an outright "no". It could be a soft "we'll see" / "let's wait to review time" / "we can give you this great new project with new responsibilities and maybe if that goes great" which keeps some people around for a bit longer without giving them a raise.