It has, in fact, attempted to marginalize everyone who did not agree with the theology and politics (a lethal combination there) of the Resurgence, and now the old guard is getting kicked in the teeth by the inevitable generational change. The younger pastors have for many years sought to distance themselves from denominationalism, and the old guard figured the young pups would eventually come around to the denominationalism the old guard hated when it was on the outside but loves when it's in control of the levers of power. Imagine that.
The SBC will be changing. I hope the new folks have enough sense to focus on its only real rallying point — cooperative support of missions. The SBC was founded with an eye to becoming a true denomination, but it never really became that until the Cooperative Program was established. But that was on the basis not of common theology but of common desire to send missionaries. The Cooperative Program is the linchpin of the denomination: Southern Baptist poobahs cannot compel churches to contribute (although they may try) and without it there is no Southern Baptist Convention as such.