very naive to thinks its the end
Huh?
<edit>
I fail to see your point.
Valve decided to stop the experiment, bringing the 'paid mods for Skyrim' project to the end.
And has said that when they decide to offer a paid mods option, they will learn from their mistake: messing with an established modding scene.
</edit>
Yes, it is definitely the end of Valve's first attempt at introducing paid mods.
It didn't work out, so they decided to back track and end the arrangement.
That has nothing to do with naivety. That's a fact.
And if you read the announcement, you will also learn that they will probably try again in the future.
This time, they will learn from their mistake, and choose a game for which there isn't an established modding community.
You make mistakes, you learn from them. That's life.
And that is how it should be. ;)
What would be really naive would be to not learn from it at all.
Luckily, Valve is not that naive.