By then I'm sure the circular economy will be larger and more established than it is now. The tools will be better as well. If there is demand for something it will be met even if it is at a higher premium.
But the options I can see right now are cash(doesn't exist in this scenario), buying things directly (if you can), swap to other "clean" crypto on DEXs or p2p platforms, and/or trade for digital fiat p2p. People do all these right now. For everyday stuff you can also use gift cards or proxy purchases. There are probably more that I'm missing