I hadn't heard the USFL was coming back, but then I don't follow pro football that much any more. None of these "new" leagues, going back to the WFL of the 1970s, have ever played at a level comparable to the NFL, or even the CFL for that matter. To succeed, a start up league has to find the sweet spot between quality play on the field and manageable finances. The WFL and USFL went broke trying to compete with the NFL by luring away NFL talen. Others like the XFL and UFL failed because they played at about a high college mid-major conference level, few were willing to pay pro football ticket prices to see MWC caliber play.
The one start up league that did succeed was the WLAF, later morphing into NFL-Europe. It lasted around fifteen years, primarily because it was backed financially and staffed (both players and coaches) by the NFL. It was more less the pro football equivalent of AAA baseball, a feeder league that sent a fair number of players to both the NFL and CFL.