Next Using the OGL Would be "Good" for the D&D Ecosystem
Based upon what I know of the 3.x "prime" era, the 3rd party products seemed to contain some level of admixture of new rules and content. I personally have been satisfied with the crunchiness of the official and also numerous other vendor products sharing the same core mechanics. What fascinated me was a good setting or flavor of fantasy adventure, role-playing, strategy and tactics. (This is based upon having accumulated and reviewed hundreds of physical resources, and thousands of digital resources.)
Consequently, I would publish one or more resources that tailored the open rules into a cohesive, interesting, and unique enough play experience within a familiar framework. (I have some excellent "King Arthur", "Dying Earth" and other 3pp 3.x materials aside from the official GH, DS, FRCS, etc., as examples of what I consider to be appealing, and would therefore want to publish.)
A simple analogy is how it has been said that a campaign could be tailored for "Swords and Sorcery" as with Conan the Barbarian. That indicates what will happen regarding magic use by players and--in contrast--denizens of that world. Some people enjoy that setting enough to commit to it whereas others do not. The new rules, descriptive text, tweaks, etc., would be popular enough to drive sales, or not.
This is my opinion, and I would plan to market to those who somewhat share this opinion. Others would market major changes to the settings or rules, including alternates or variants (e.g. magic). By the way, as a gamer I was happy to continue to look for new resources in the same 3.5 system there at "the end", and make incremental changes. The requirement to change has only ever been presented to me as an economic one for the prime vendor (because tweaking the system as some players wanted didn't necessarily require ending the existing line), and where that economic decision intersects with an existing customer base is how much money, time and effort will be required to retire or adapt perfectly good props for something newer, better and shinier, all while being told that being nostalgic is for dinosaurs.
The discussion about the licensing and control over a product line is key to the economic realities of products and services. There are proprietary and open source software models. They work. They have rationales and approaches.
I am a firm advocate of protecting IP/content. If a WotC wants to magnify its market share by providing a "standard" or "platform" where others can make money, that is great. Consider the number of open and proprietary software programs that run on Windows (operating systems), and also sometimes compete with Microsoft products (software applications)--MS commands so much market share for OS's primarily because there is so much do there, beyond what they could ever practically provide themselves. But also consider how MS got into the console market because ostensibly they can better control 3rd party product quality--but really, they get a share of every physical cartridge.
If WotC wants a share of every 3pp product, there are analogous examples, and some will take advantage of the situation, and there will be some market for it. (like consoles or some smartphones)
If WotC wants to invite numerous vendors to make money on their own content while running on a standard platform (and agreeing to certain guidelines and respecting the rights of the provider), then that will work too. (like 3rd party apps on Windows or other popular OS)
If they instead want to be their own internally participating ecosystem of publishing because of their greater resources, then, of course, that is already in play. (like a consumer device where changes are only driven by the vendor)
So to me, it is really a question of what business and financial short and long-term considerations will become pre-eminent to the decision-makers for this 800 lb. gorilla in the role-playing market space.
I will transition, as a gamer, if there is something appealing about the ease and consistency of this next edition, without changing the flavor in a way I do not prefer (like emulating MMORGs). I will participate in that market as a provider if there is a (friendly) standard and contributors receive their due rewards for effective marketing of quality products, while practicing good business. As has been said by others in previous posts, it need not be a "zero sum game."
