Why should the hang outs be co-ed. Rabbi Wallerstien made kosher hang outs in the catskills this summer that was very well attended but he made it separate for boys and girls, he had no problem getting kids. If it is free, they will come.
You are unfortunately correct, there are many kids and even adults that are going through the motions but they aren’t really frum, they are all burned out and turned off. We are living through very difficult times. It is really sad.