On the other hand, being able to wipe a few times would dramatically extend the mission lifetime. If InSight had been launched with a brush attachment instead of HP^3 then it would likely have another decade of service ahead of it running the other experiments, especially the seismometer. Eventually other parts will fail, especially the onboard batteries since there's not really any such thing as battery chemistries that have indefinite lifetimes, but then again this is more of a hindsight observation.