It's been a while since I coded anything, let me take a whack
10 Print HELLO
20 Print How much are Bitcoins?
30 Input 8-8
40 Print Bitcoins are $Input
It may need a few tweaks.
It's hard to answer your question though (as what would happen) because I'm not even sure -how- that would happen, which would alter things, on top of getting enough clients to switch over to the fiat-pinned version.