Cool as this idea sounds, and I mean I voted yes to it being made as well, what could his shield become? The best I've got is that when he uses his ult he rolls out a red carpet in stead of giant ice crystals, but that sounds more fitting for a butler or stage hand than a high society gentleman.
The only other thing that makes me pause is that the current gentlemen skins are meant to satire the usual character of the people they are on. Cho Gath is actually a horrific monster from another world and Gragas is a lack of social rules type of drunk. taking that into account, a gentleman skin wouldn't fit him.
Now a debonair skin on the other hand is free game. Cause how does Braum's theme not scream "ladies man". Especially with that mustache -->