> If eighteen months from now Starship has launched a ~dozen or more times and SLS once, I'd imagine they might wrap up SLS with Artemis 2, which should be mostly complete by then.
Starship needs to be crew-rated by NASA before it can replace SLS+Orion. I'm sure that will happen at some point, but that point may well be after Artemis 3 has happened.
Some people propose hybrid architectures – putting Orion+ESM inside Starship, and using F9+Dragon to ferry the crew to LEO. However, I think NASA will view those hybrid architectures as even more complex, and hence riskier, than the current SLS+Orion(+Gateway)+StarshipHLS architecture. Plus, pro-SLS forces in Congress will oppose NASA doing that. Bridenstine proposed launching Orion on Falcon Heavy, and Senator Shelby's response was to ask Bridenstine for his resignation. Shelby may be gone from Congress but there are other members of Congress with the same attitude. It is harder for Congress to oppose a NASA project to crew-rate Starship because it would be less obviously directly competitive with SLS+Orion, even if the death of SLS+Orion would be its ultimate consequence.