The long range impact of the OGL is not over as Pathfinder is still using it and in my opinion, as a gaming company, using it in a manner that leverages their brand far better than WoTC ever did. By providing spot light information, by selling the products, by continuing to add to the overall pool of OGL rules, Pathfinder keeps things moving forward.
WoTC has tried to 'go it alone' and let's be honest, no one outside of WoTC knows how that's worked for them. But from an outsider's persepctive, no matter how much more I enjoy monster design and NPC creation in 4e, 4e does not appear to have met WoTC needs or we can expect a huge amount of chrun between editions in the future and were lucky to have 3.0-3.5 as long as we did.
