This is true. But it is not true that 3.xe was a success because it was under the OGL. After all, as many people suggest, Wotc did not support the OGL beyond the core books and arcana unearthed.
No. This is your suggestion but it does not follow from any facts that it might also be true. After all, many 4e fans complain of rules and product bloat and if it were not for the DDI utilities they would have had a very difficult time to follow new products. Some third party publishers tried to publish for 4e but they stopped since their sales were very low. They believe that 4e fans did not want third party material because it were not compatible with the DDI online tools.
Maybe, maybe not. As noted above, a number of publishers tried to support 4e with the GSL but they did not have any luck in the market. OTOH, the OSR is experiencing significant growth. The OSR would never support 4e, even if it were OGL, yet it is doing better than 4e third party publishers.
Where do you see "maybe not" in the last paragraph? Did Paizo not try to do make 4E material, or did they not back off after seeing GSL? Both of those things are true, so it's a natural conclusion that with an OGL, there would be no Pathfinder (because Paizo would not have backed off of 4E).
In the second paragraph you're arguing that 3PP material is not a major staying factor for an edition. It isn't? Then what's holding the players outside the official material? Wizards can produce only so much material for D&D. With OGL, more people can add that material. More 3PP, more material. More material, more potential hooks for people. More hooks, more time spent playing. More time spent playing, more people still buying the official books seven years after game's release. Pretty clear and obvious logic.
WotC did not support OGL beyond core books... what... I'm not sure I understand that statement, as it stands now, it's going against what OGL is.