Did they close your trail altogether, or just to mountain bikes? Can you find a trail that you have to drive to? I'm going to get a mountain bike in the fall, and I will probably have to drive it to any trail, but it's not like I've ever had access to one otherwise. I drive me and my dog to a trail to go hiking but they don't allow mountain bikes there.
As far as little kids taking your commitment from what you like to do, that won't last forever. I have old teenagers and it seems like they were born yesterday. Something always did crop up when there was something important to do. Like the time my daughter got a dangerous case of hives.
I didn't actually start biking till they were older. I don't race, just centuries to train for.