The average CCW type probably doesn't even carry the gun that much. An informal poll by TX CHL instructors found 80% of their students didn't. I'd better a similar majority have no training beyond the TX CHL class. I doubt they shoot their gun even once a month.
So after reading, this thread - I conclude that USPSA probably cannot attract the average CCW type on its own. Nor can IDPA. The motivation is some external to the gun games, internal to the person and those that have will find a competition they like. That was my story - when I decide to carry a gun, I decided I needed to train and then that led to various competitions. It was internal to me.
Now, if you can get a person to the game - being supportive, etc. is good.
The IDPA vs. USPSA - we are the better - boring. Shoot what you like and is convenient. Want to dress up like a bumble bee with logos fine. Want to wear a concealment vest that you never wear out - fine. Want to look like a cowperson - fine. Want to shoot steel with something that looks like a photon blaster - fine with me. Want to have an AR with every accessory including a George Foreman grill in the stock so you can make a burger between 3G stages - sound yummy.