The "doubles" idea isn't a great one, but I can think of many worse ways of forcing pro athletes to compete twice in a span of 3 days, 4 times per year. They don't have a large enough prize pool to let athletes choose which two events to compete in because that would increase the number of "winners" from 6 to at least 8 or 9, and a key part of this working is the guaranteed floor of $40k for the athletes who finish 8th each time.
My main complaint/suggestion is to drop the 3000 and replace it with another 1500. First, it's a weird distance that nobody cares about and goes against the idea of keeping it simple for viewers. Second, as others have pointed out, it's not different enough from the 5000 from a viewing perspective. But most importantly, I'd much rather see Nuguse, Ingebrigtsen, Hocker, Fisher, Nico, etc duke it out in a 1500/5000 double than watch someone like Nuguse lose a bunch of 800s to Hoppel just so he can compete in his primary event. Let Kerr, Kessler, Wightman, and (yes) Eric Holt take on Hoppel and Jewett .
That means we probably don't get Kerr vs Ingebrigtsen 4 times per year, but I'm fine with saving some of the best rivalries for the events that matter (Olympics, Worlds) if it means we can have a league that actually pays top athletes a decent amount.
If it's an American-centric league that can only pull a couple non-US-based athletes per year, I'd be up for watching something like the following sets of athletes:
800/1500 Men: Kerr, Wightman, Kessler, Holt, Arop, Hoppel, Jewett, Cohen
800/1500 Women: St. Pierre, Hiltz, Mackay, Ramsden, Mu, Akins, Reekie, Muir
1500/5000 Men: Nuguse, Ingebrigtsen, Hocker, Fisher, Nico, Sahlman, Teare, Kejelcha
1500/5000 Women: Cranny, Schweizer, Valby, Hassan, Weini, Jess Hull, Infeld, Rogers