No, it's stagnating because of a growing income inequality and a hollowing-out of the middle class. Innovation isn't enough to fix this, and eventually it's going to bite us in the ass. But infrastructure is also important for the economy, and US infrastructure is in a shambles and getting worse. Big infrastructure projects (which actually work) are desperately needed, especially ones which make transport more efficient and less polluting. I'm not entirely sold Hyperloop is really the answer BTW, I think SkyTran would be a lot more useful overall and a lot more technically feasible not to mention cheap to build, but I see the same naysaying for any new transportation technology that comes along.