It affects people with a specific type of loan. From another article:

At the center of the change are borrowers who took out federal student loans many years ago, both Perkins loans and Federal Family Education Loans. FFEL loans, issued and managed by private banks but guaranteed by the federal government, were once the mainstay of the federal student loan program until the FFEL program ended in 2010.

Today, according to federal data, more than 4 million borrowers still have commercially-held FFEL loans.

So basically it will affect 4 million people with loans taken before 2010