The price'll fit to the demand. If demand wanes significantly after the price increase, then Microsoft probably won't do it again, it might even lower the price. If it doesn't wane, then, yeah, Microsoft would be correct in the assumption that it's fine to do it again. It's fine until Microsoft starts losing money, that's the bottom line from what I can see.
What if you never agreed to the EULA before jailbreaking it?