Would be pretty cool to see , but I don't really see the point. Bitcoin is doing fine gaining more awareness simply by more places accepting it and more companies/services popping up making it easier and safer to use.
There is a company/organization who is doing something similiar out near San Francisco , you can read about it here.
http://www.coindesk.com/arisebitcoin-40-bitcoin-billboards-san-francisco-bay-area/While it would be nice to see something like that on time square I agree that the money could be better spent elsewhere. If I had a $1million dollars to help educate people about bitcoin I would invest in one of the many bitcoin related startups out there that I think are really advancing how quick adoption to bitcoin happens.