I understand that, I don't believe it can work because businesses will update their software in time, but if someone neglects to do so, it is possible and it can go bankrupt in a second...
If bitcoinXT wins I'm pretty sure we'll see a couple of "legacy bitcoin" holdouts for a while, and for a short time we might also have a good chance to find some smaller exchanges on both chains. So I'm pretty much optimistic about doubling my BTC holdings

. I also expecting to see some bottomed out BTC and inflated altcoin prices as fiat sources can dry out quickly after the first big BTC dumping wave.