My wife has an Arkansas driver's License, though it's not one of the new REAL ID licenses.

The DHS says:

Starting January 22, 2018, passengers who have driver's licenses issued by a state that is not yet compliant with REAL ID and that has not received an extension will need to show an alternative form of acceptable identification for domestic air travel. Please see TSA's website for a list of acceptable forms of identification. Passengers who have licenses issued by a state that is compliant or that has an extension to become compliant with REAL ID requirements may continue to use their licenses as usual. For a list of states already in compliance or with an extension visit DHS's REAL ID webpage. DHS continually updates this list as more states come into compliance or obtain extensions.

The TSA says:

Adult passengers 18 and over must show valid identification at the airport checkpoint in order to travel.

• Driver's licenses or other state photo identity cards issued by Department of Motor Vehicles (or equivalent)

...

(and then links back to the DHS site).

Which one of these do I believe? The TSA doesn't list anything else besides a passport - she doesn't currently have one, so does that mean that we need to either get an updated REAL ID driver's license, or a passport? Or is a current Arkansas driver's license valid for travel?