I don't think Dark Sun will save WotC, but I sure as hell don't think it'd hurt it to release a 5E version.
Dark Sun has a couple of major problems. And I say this as a major Dark Sun fan from back in the day.
The main problem is that it's trapped between a psurlon and a hard place. If you keep all the stuff from the 90s version, there is a significant number of people who will rail against both it as a concept and you as a publisher, notably the oppressive themes up to and including common slavery. And if you soften that edge, the grognards who you were relying on to build interest in it will rail against it because it's not "real" Dark Sun. That's a lose-lose situation.
The second, significantly smaller problem, is that Dark Sun is
weird. A single hardback isn't going to suffice to provide the detail level needed to do a good job with Dark Sun. And second-degree sourcebooks generally don't sell all that well.
I find interesting that people keep repeating creative commons and ogl and public domain. How would that turn profit for D&D? It's like people skipped over part in this scenario where we need to make D&D profitable. Too bad OP didn't include part about what would we do if we invested all we had into this business with all or nothing outcome ( aka if dnd isnt profitable, we lose all and become broke and homeless). I bet there would be less "run it to the ground" comments
That depends on whether the owner wants it to provide the same RoI that they expect from the stock market or if they're fine with it paying for itself.
Just asking why go that route and not copyrighting or trademarking everything thats possible and then licencing out IP for profit?
Steampunkette had some good reasons for not doing this, but there's at least one more. Doing it that way is a lot of work. You need to hire people to
manage those licenses, and make sure that the licensees stick to their agreements, pay what they owe, and that whatever is released is something you can support. With an OGL-style license, you just let people do their thing, and you don't need to bother with it unless someone does something egregious (e.g. the Book of Erotic Fantasy).
And this does not just affect
you. It also affects your licensees. Under the OGL, if I want to release a 5e adventure, I can just do it. I mean, I still have to do the work to write it and stuff (or pay someone to do it), but it's under my control. If I have to enter into a licensing contract with Wizards, I need to approach Wizards about it and negotiate a contract. That's a lot of work and will probably need a lawyer, which eats into my profits, making doing so a less attractive deal for me.
Remember that the original plan with the OGL was that it was win-win. Smaller fish get to handle making adventures and sourcebooks and stuff, which a big corp like Wizards has trouble getting to a level where they make sufficient RoI to appease the beancounters. That lets Wizards focus on the big flashy luxury items while still making sure there's a lot of adventures out there to get people playing. To use early 3e names, The Crucible of Freya is not competition for the Sunless Citadel, it is an ad for the PHB which Wizards didn't have to pay for.