At least in Germany, the Maker Faires still seem to be doing fine. They are done by Maker Media GmbH, which is part of Heise Publishing Group (they do the c't and iX magazines). They don't publish numbers on how specifically Maker Media is doing, but at least the Maker Faires seem to be doing OK since they pretty much have record visitor numbers every year and are expanding (the one I go to in Hannover will expand from 2 to 3 halls this year).

I guess the trick is to find the sweet spot in the exhibitors. You need to have plenty of "real Makers", otherwise the Faire loses its spirit, but you also need commercial exhibitors from which you can get "real" money. I remember from last year in Hannover, the big commercial exhibitors were Nintendo (who showcased their Labo stuff), Volkswagen, and Conrad Electronics (big reseller here in Germany). Also, lots of food trucks outside. But all in all, it was still acceptable in my book, and my kid loved it. So I think this can well be done with profit, but I guess that being part of a big technical publishing group also creates lots of synergy which saves cost.