"This would make my middle aged life" exactly. bring back ALL of the remaining original cast. i think Tom Felton should be Remus, or something. Gary Oldman would make a good Dumbledore. or Jason Isaacs. or Ralph Fiennes.
Actually, we Potterheads know this is not Professor McGonagall because this cat does not have the markings around the eyes that resemble her spectacles. Also as if it's perfectly normal for a cat to be reading a book