Even if they don't get to a no replacement....they still already have a massive improvement over Space Shuttle. The Space Shuttle basically every tile was unique, and and the pattern was different between the different orbiters. A good bit of the months of refurbishment of the Orbiter between flights was heat shield repairs. SpaceX has already shown from when they completely retiled one of the ships. they have cut down the time to replace a single tile down to minutes instead of the hours it took with the shuttle. The Tiles are also alot more standardized so they can be more mass produced than shuttle tiles.