USL doesn't need true nationwide relevance. They need to be a strong local product in the metro areas that MLS doesn't want/need. Get the local done, and keep dealing with something like ESPN, and the nationwide relevance will be a byproduct even if it never matches MLS. Even now, not counting the MLS2 teams, USL has 5 of the top 25 MSAs (Phoenix, OCSC [Irvine], Tampa, Charlotte, San Antonio) and there's talk of USL teams in 2-3 more in that range. You've got 53 MSAs right now over 1 million in the US with it looking like the next census will move to 55 with Tulsa and Fresno both topping that mark. Viability seems more and more likely every day, even though the safe bet is still a lot of volatility in the coming decades.