Thanks! I agree although I would make the replaceability concept even stronger, promoting it from heuristic to definition. My reason is that the proletariat is defined by the fact that the commodity they sell is not objectified labor, not a finished commodity, but labor power, the potential to labor. A movie star sells not labor power but a different commodity, their brand. The question of who is proletarian can be simply answered by which commodity they sell. Awoo made the good point that these actors might be called artisans, who sell finished commodities rather than labor power.