Again from Greg Tito's article:
"We'll have more information on the GSL as it relates to the next edition in the near future. Personally, I have a copy of 'The Cathedral & the Bazaar' on the shelf at work," Mearls said, admitting the landmark essay regarding open source software systems impacts his views on the subject. "From my days as a programmer and as a freelance RPG designer, the bulk of my work involved open platforms which did a lot for a game that relies so much on individual creativity."
'The Cathedral & the Bazaar' is a seminal work that encapsulates how Open Source software works better than proprietery software. Just replace software with "gaming system" and you will get the picture.
If you think open source software is a bunch of hooie than you aren't paying attention. All of your phones either run on Linux (Android) or BSD (Apple). In fact all of Apple's operating systems run using BSD at its core. Linux runs your Tivo, and tons of other little smart devices. Oh Linux also runs most of the Internet that you waste your time on all day. Ever heard of Facebook? Runs on Linux. Google? Runs on Linux. Yahoo? Runs on Linux. Whitehouse.gov? Linux. And on and on.
The reason you can still have a thriving 3.5 edition D&D game with new content coming out all the time from Paizo? Three letters. OGL. O as in OPEN people.
I firmly believe that one of the reasons that 4E didn't do as well as it could have is because it wasn't as open as 3.5. No one but Wizards could easily create content and paricipate in the 4E world. That left Paizo with no choice but to jump in whole heartidly to 3.5 and the OGL. It left WotC on an island of their own making. Frankly when 4E first came out it was almost a deserted island comapred with the lush tropical island of 3.5. There was very little content from the rule books or adventures.
Openess encourages systems to be compatible and play nice with each other. In other words, it breeds standards. Linux and BSD are nothing but little programs talking to each other in standard ways. It allows you to create code that can compile and run on either system without making much if any changes.
5E sounds like it would do very well to be as open as possible. Why? If its as open as possible then it will work with Pathfinder as well. And why not? After all, its called the OPEN Gaming License people!
Mike, you will be my hero if you make 5e as open as the OGL was. Do me a favor. Take that book on open source, make copies, and put it in all the bathrooms at WotC and at Hasbro. Everyone needs to read and understand the open source culture and the huge impact it has had on our modern world.