Bitcoin is ultimately deflationary. After 2140 it is 100% deflationary because no new coins will ever be created, and the supply will keep naturally shrinking as people make mistakes and lose them (I doubt anyone will be willing to burn Bitcoins because by then 1 Bitcoin will be worth several billion dollars).
The price of Bitcoin will increase and goods will get cheaper. Don't forget the fact that you can divide Bitcoin into many decimals.
So problem solved.