During the Bethesda press conference, they announced something called 'Creation Club' for Skyrim: Special Edition and Fallout 4.

It seems like their equivalent to how Valve brought in community submissions of purchasable items for Team Fortress 2/ CS:GO / DOTA2 and then gave those creators a cut of the sales. Although they say there will also be purely internally developed content as well.

It seems that the external submissions will all go through at least some level of internal checking, and you'll need to apply to be a 'Creator' first. From their Q&A:

• Creators are required to submit documentation pitches which go through an approval process. All content must be new and original. Once a concept is approved, a development schedule with Alpha, Beta and Release milestones is created. Creations go through our full development pipeline, which Creators participate in. Bethesda Game Studios developers work with Creators to iterate and polish their work along with full QA cycles. The content is fully localized, as well. This ensures compatibility with the original game, official add-ons and achievements.

Of course, a few years ago Valve and Bethesda tried something less structured in allowing paid mods for Skyrim and it was a huge mess. Here's the Q&A answer trying to steer away from if this is 'paid mods':

• No. Mods will remain a free and open system where anyone can create and share what they’d like. Also, we won’t allow any existing mods to be retrofitted into Creation Club, it must all be original content. Most of the Creation Club content is created internally, some with external partners who have worked on our games, and some by external Creators. All the content is approved, curated, and taken through the full internal dev cycle; including localization, polishing, and testing. This also guarantees that all content works together. We’ve looked at many ways to do “paid mods”, and the problems outweigh the benefits. We’ve encountered many of those issues before. But, there’s a constant demand from our fans to add more official high quality content to our games, and while we are able to create a lot of it, we think many in our community have the talent to work directly with us and create some amazing new things.

So free mods aren't going anywhere... unless a creator decides that they are only going to submit their work through the Creation Club. I'm not really sure if they explained it well enough during the stage show to stop people from thinking that this is an exact retread of the last time though. It once again raises questions about how they can vet this stuff to make sure modders aren't using other modders' work.

It also raises questions about how mod makers should be compensated in general. If someone spends time making a quality mod that is used by millions of players, should they be compensated? Or is just doing it 'out of enthusiasm' an unwritten agreement? Bethesda have long been supported by modders with their games so it seems like some possible method of repaying them is worthy, but how it will shake out in practice remains to be seen.