Taubes' simply connected symplectic decomposition conjecture

Let $X$ be a smooth, compact, oriented, simply connected $4$-manifold without boundary. A connected sum here means a decomposition into smooth four-manifolds, and both orientations of each symplectic summand are allowed. Taubes' simply connected decomposition conjecture. Every smooth, compact, oriented, simply connected four-manifold without boundary is a connected sum of symplectic manifolds, with both orientations allowed. This is a refinement of the preceding decomposition question restricted to simply connected four-manifolds. The source states that this conjecture remains open.