They'd convert most of them to cash, which is what everybody else in the world is doing anyway and use them to avoid processing fees to Visa and Mastercard.
The current bitoin market by in large isn't "cycling money" either, it's all speculation. If people were using it mostly for goods and services it wouldn't be fluctuating in price like a penny stock.
Which would cause Bitcoin to become worthless. A site like Amazon wouldn't throttle Bitcoin expenditure. It is exactly why Amazon won't accept Bitcoin for a long, long time. Once many more small sites start accepting Bitcoin, then we can think about the big dogs.