NASA has always used private firms to design and build practically everything. SpaceX will be constrained by the same things as all the other private aerospace

NASA has always used private firms to design and build practically everything. SpaceX will be constrained by the same things as all the other private aerospace and defense contractors: export control restrictions, domestic production laws, and most importantly the loss--and transition to a domestic rival--of a huge (even primary) customer if that customer should be displeased with their choices. If SpaceX (or Blue Origin or whatnot) manage to transcend the need for US government money, well, good for them. They just created a huge new swath of economic activity, which is exactly the goal of NASA in supporting commercial services.