I have an "@mac.com" address.
If I don't go to icloud, will it still work?
I can't see any immediate reason why not.
But you'd be well advised to buy yourself a straightforward "kwackman.co.uk" (or similar) address and start publicising it among your contacts. Set it to forward to your mac.com address for now. But this address can follow you through life, despite anything Apple (or any other company) throw at you. Take control!