Well let’s see... No x brace, no steel string (jazz boxes excepted), no steel string pre war maybe no popular take up of guitar (or even development of jazz boxes) (Victorian fashion for parlour guitars notwithstanding, having died out by then), maybe Les Paul/Adolf Rickenbacker/Travis Perkins (take your pick) invents first electric banjo or ukulele, or harmonica or accordion, maybe Jimi Hendrix revolutionises folk fiddle playing... But that’s not even the point. FFS it was just meant to be a bit of light hearted fun and discussion starter about the nature of the guitar and who made a difference at some point, not a bloody PhD thesis.