It's pretty nuanced and contextual. I guess the shortest way I can put it is that co-ops can ameliorate some of the worst aspects of capitalism and improve people's material conditions as well as serve as a site for radicalisation, but it can just as easily just operate as an otherwise ordinary buisness with no revolutionary potential. Also, unless the co-op is engaging in revolutionary activity somehow, eventually they will be subjected to the same intensifying competition all business do and so they must make concessions all the time (lower quality of goods, lower everyone's pay, abandon the co-op model, sell the business, etc ). Rosa Luxemburg wrote plenty on this in her polemic against the revisionist Bernstein, Reform or Revolution.