The whole thing is a mess and just terrible however you look at it. At best, it sets up a hard wall between future "OGL" materials by third parties and decades of Open Game Content. If you sign on to this, and supersede the OGL 1.0a for yourself, you can't use any third party content without violating the copyright holder's rights. You could take your own original content that you released as Open Game Content and use it in something released as OGL1.1. But you can't use anyone else's OGC, or
you are violating the OGL1.1's clause that "Your Licensed Works do not and will not infringe upon any third party’s intellectual property rights or any of Our rights not licensed to You via this agreement or any other." (Remember, by agreeing to the OGL1.1 you voided your participation in 1.0a and so using OGC except the WotC SRD is an infringement of a third party's IP.)
One of the great values of the OGL 1.0a is that it sidesteps the orphan works problem of copyright law. You know how we've lost so many works of the early 20th century because no one would take a chance on publishing or invest in preserving, due to ambiguous legal status? Open Game Content can be used and re-used and derived-from even if you can't reach the copyright holder or even determine who it now is if, for example, someone dies.