Agree to disagree.
Glenn's voice was just as great and unique as Don's is. To me, Glenn was the better singer overall but I think there would be plenty who could cover Henley just as good as Vince and Deacon are covering Glenn. And I don't say what level that is, I think it's known I don't think very highly of it. Glenn was the frontman. He directed and led the show and his voice was the one that people heard out front and center every night. He would be just as hard to replace as Don.