Will pick up on this thread this time next year to see how accurate you are. I'm feel certain free mods are not going anywhere, but of course there will be people who would like either the ability to choose a "pay what you want" method that scales to free, or would like to be paid for their time and effort. We'll see
They aren't going anywhere, that's for sure.
Before: you can make and release a mod for free.
After: you can make and release a mod for free.
And then some people that feel they can't spend time for free on content can now make content that wouldn't have happened otherwise.
It's funny how people were cheering on deep Steamworks integration into every game and now it's suddenly a problem, lol