1. Exchange tokens?
2. Web3?
3. App tokens?
4. ?
What do you think?
CBDC potentially being used by all of those service. Don't you know the main purpose of CBDC? it will become a fiat digital and that's pretty similar like USDT or any other stable tokens that exist in the market. I think that it will not be specifically used by some service. All of crypto service can used CDBC as a payment option as well consider it was digital fiat money.
You must need to know that if stable tokens are also used by all of services in the crypto like those you have mentioned above.
I think that CBDC will not make only a few services became successful.