I'm wondering if these will be songs that Glenn recorded or ones he didn't get around to:
“We’re all missing Glenn and this great space he left in our lives,” said Tempchin, who will release an album early next year featuring new recordings of songs he wrote with Frey. “He had a lot of further plans and things that he was doing that aren’t going to happen. That kind of dominates the mood. It’s kind of celebrating what he achieved in his life. He was the fire that kept it burning.”
Source.