Some eggheads have wargamed this, and the consensus is/was that surface dwelling would be impossible. If the Earth kept spinning, the core could stay warm enough for us to live, but it would be absolutely nothing like what we know.
The rotation of the Earth has absolutely nothing to do with the generation of heat in the Earth by the decay of natural radionuclides.
(Perhaps you are falsely conflating that with the maintenance of a magnetic field, which does indeed depend upon the continued existence of a liquid core in which thermal convection generates a magnetic field?)
Regards,
Boring Company IPO?