Today, validators working on
@Polkadot's cores check that parachain blocks follow their rules, keep that data available for 24 hours, and take part in consensus.
To use a core, though, you have to be a parachain.
JAM opens that up. Any code built for its virtual machine will be able to rent time on a core directly: smart contracts, agents, media serving, regular software.
Parachains keep running as one kind of service among many.
Same cores, open to anyone who needs compute. That's what the cloud did for servers.