If it were me, I'd ask them for specific reference to why they think they don't need to return the fees if they cancel the flight. According to the U.S. Department of Transportation, they have to, and I see nothing from the government saying otherwise.
https://www.transportation.gov/indiv...-cancellations
Of course, if you rebook, or accept whatever changes they propose, then that's that. But any time your airline cancels your flight and offers you a schedule change as a result, you should first look to see what tickets are selling for right now, then decide whether to have them refund your ticket and fees then independently rebook online, or just accept what they're offering. Not surprisingly, no airline will tell you about this.