State services are really the only clear need for unions remaining. The sheer volume of people and need in this country is going to do nothing but skyrocket, with their compensation being left up to dipshit citizens and politicians who will only pay them if it's politically advantageous.
In the marketplace, a new paradigm has existed for a few years now where taking care of employee work conditions is part of marketing and brand, thus intrenching appropriate compensation. Union leverage is fading fast because of this.