Idk, I think Pegg could handle it in a vacuum, but it would change his dynamic w/ Butcher a lot and even more w/ Annie(who I thought was great. I never really cared for her in Jessica Jones, but she nailed this). I can't see pairing a 50ish Pegg w/ 25 yr old Moriarty(who plays younger than that), and I don't think an aged up Annie would work, more so than an aged up Hughie.
Urban is perfect as Butcher. I like the actor they have playing The Frenchman, but I kinda wish they wouldn't have changed his personality so much. There was something great about this ridiculously over the top affectionate Frenchman that was also a brutal killer.