This is the major, systemic problem to me as well. I think there needs to be more innovation within the financial model of multi-sport games.
We live in the age of streaming, and yet many major events still rely on traditional broadcast deals. I’ve always wondered how events would fare with a pay-to-watch platform similar to europeangames.tv. We’ve already seen a few sports trying this model with Recast or “in-house” platforms. Of course, price point(s) need to balance money brought in versus people willing to pay (which might be difficult).
Additionally, more public viewing centers could be set up in host cities for locals/visitors if stadium capacities are smaller. Charge a small fee to enter such areas, and allow local vendors to sell goods inside (along with your merchandise).
Use of existing venues should be imperative as well. New venues should emphasize cost and function over frills and splendor. It might be wise to reduce some of the venue capacity requirements as well, especially if people have easy access to coverage of the event online or at public watch parties.
Those are just a few suggestions. I don’t know how realistic they are, but clearly some new ideas are needed in this sector. It’d be a shame to lose a bunch of multi-sport games in the future.