The purpose of the USFL is to provide Fox and NBC programming during the spring/summer lull. You cite that other leagues were doing better than the USFL. That is not true. After the initial curiosity viewing both the XFL and USFL settled in around the 1 million viewers per game mark. You also forgot, or do not know, that the USFL is owned by Fox and NBC. So I seriously doubt these networks went into this venture unaware of the viewership potential.
You are correct that it's entirely likely that Phase 2 of the USFL, moving the teams to their home cities, may not happen. I don't think it would be worth the added expense. The single hub city concept works fine, other than the lack of fans when the home Stallions aren't playing.
None of this has stopped ESPN/ABC from signing on to the XFL's return next spring. The XFL plans to begin play earlier, with teams in home cities, right after the Super Bowl. So there will be two spring leagues in 2023, though not playing head to head, as the USFL doesn't begin until April.