It wouldn't create any income due to the electricity costs associated with mining, unless the users start buying ASICs. Also the most straightforward way of implementing this would be by having the user spending the token they generated in a transaction to prove their work, which would nullify their income. Maybe there is some workaround by monitoring the blockchain and seeing if a certain user generated some tokens at a certain time, but would it be worth the extra energy required due to the use of bitcoin' PoW? I think no.