Sadly this is unlikely to happen for anything above indie/niche games, unless the newcomer has some sort of groundbreaking advantage: first, these platforms also act as ad/exposure for game studios with limited advertisement budget by giving them access to a massive existing audience, which you're just not gonna get at this point from a new platform, and second (and more pernicious) they all have some sort of price matching clause, so if you want to take advantage of lower fees to cut the prices on the new platform and attract more people there, by contract the incumbents can adjust the price of your app unilaterally, cancelling out this move. There is also the fact that not all 30% are equal, so to speak : for example, Steam gets a lot less bad rap than the others due to the amount of tooling/services they provide. There is no easy fix to this situation.