Starship is _required_ as part of the TLI trjaectory to refuel SLS with cryos. NASA will keep flying SLS however, to demonstrate to the public and congress that it was not setting a pile of tax dollars on fire. LH2 as a fuel was a mistake, high ISP, but well, the turbopumps, plumbing, valves, etc, not to mention REFUELING LH2 ON ORBIT to replenish evap. Starship imho will lapse SLS in the next year or two. From a perspective of demonstrated spaceflight capabilities per unit cost, it will lapse it the first time Starship makes an uncrewed flight around the moon and re-enters a capsule that is recoverable with a human survivable water or land landing. Key qualifier there is per unit cost. Point is, Starship lapses SLS once it matches demonstrated spacelfight capabilities on sheer demoninator of cost.