As an entrepreneur in this space, I'd be okay with 20%. The issue is the current thresholds. I'd want it to be 20% over $1M not $50M. Around a million it starts being worth it to handle credit card processing, chargebacks etc.
As there’s more competition from studios entering the publishing space you should be able to get a better deal, with better and more current tech. The up side is Steam gives you visibility to a large player base with new publishers won’t have on day one, but it’s coming.