I predict that as time goes on, companies like WoTC will have their market share eroded by small publishers. Never enough to put them out of business I think, but enough for them to notice and try to understand why. The people at WoTC who play games will understand but the bean counters who get to decide things like production budgets will not. Large corporations seek safety. To make the profit needle move, they must have huge sales. Huge sales require huge audiences. In order to get huge audiences, the material must be what you'd expect. The unexpected, the unusual, the experimental, the difficult is not something you can sell to the largest possible audience. Eventually, WoTC will attempt to emulate some of the small publishers but it will always be just safe enough to keep it from producing anything truly interesting or truly unexpected.
The little guys will continue to make interesting things. Other people will say, "I can do that too." So they will make interesting things. Eventually, enough interesting things will be made that people who are tired of buying The Expected will only buy The Unexpected. That may only ever be 10% or 15% of the total RPG market but for the people who make The Unexpected that will be enough to keep going.