Funny that you're wondering how many people are going to pick up the sport these days. Well, there's actually record numbers of people taking up the sport this year. Disc manufacturers can't keep up with the demand, and memberships in the PDGA have exploded. Disc golf is taking off like a rocket with no let up in sight. CBS Sports is even covering the disc golf Pro Tour this year.
I've been a crazy avid disc golf fan for all of a year and a half now, and play about 2 tournaments a month. If I had to choose between disc and ball golf, I would choose ball. But I have invested enough money and time into disc golf that I now have another sport to go out and play that gives me lots of exercise since there are generally no riding carts involved, and some courses are located in parks where you have to hike up hills and trails to get to your next shot/hole.
I find it more frustrating to play because of my competitive nature than ball golf, but I've been playing ball golf for 30 years and have a grip on my emotions and swing thoughts that I'm still trying to sort out on the disc golf course. Love the sport, and a lot of people are going to love it for its accessibility, price, and family friendliness.