Congress held this hearing as part of their looking at what changes to make to the law / changes to force the companies to make, so maybe they'll look at legislation that would change the situation (for example, some way of forcing Amazon to split "platform provider" and "product creator" into separate companies).

I've no idea if anything at all will come of it, or whether anything that does will be good or bad, but this hearing wasn't just about getting verbal commitments of being good from the CEOs (despite there being several questions did ask for verbal commitments in various areas).