> but allow lenders to differentiate with rates on the basis of area of degree earned
This makes little sense in the current system, where many students don't even declare a major for their first year (or two, sometimes). They'd be halfway through college by the time they were able to know which degree they'll earn.
Intended major is just as bad of a metric. I think we all know many people who intended to go into one major and ended up in another.