The announcement was made at the 2017 NSSF Rimfire Challenge World Championship in Alabama. This is Michael Bane's post in a Facebook group after the match.

We made the announcement at the NSSF WORLDS...effective 1 January, the Rimfire Challenge Shooting Association, founded by myself and Ken Jorgensen, formerly of Ruger, will be taking over operation of the RIMFIRE CHALLENGE from NSSF.

As most of you know, Ken and I, along with the late Nelson Dymond, created the RIMFIRE CHALLENGE almost a decade ago, and we have seen it grow into the sport we dreamed it could become. This year's WORLDS were a testament to the strength of the sport.

Our first goal is growing the sport...we feel there's a huge untapped potential here!

Don't expect any major changes the first year...the sport's running just fine. It will be exciting!
I also read where Michael posted that "Mechanical" would be coming back as a full division, instead of the "special recognition category" currently used. I saw a few film crews at the World match, so hopefully some good TV coverage will help boost the sport. Waiting to see if I made it to TV or now, I was "in the background" when they were interviewing a couple people.