Rep Karianne LIsonbee and Sen. Todd Weiler have sponsored HB198, Concealed Carry Amendments, which we will know as "Concealed Carry Permits for 18 to 21 year olds." The bill's text and status can be quickly access at http://le.utah.gov/~2017/bills/static/HB0198.html .
This bill makes a permit to carry a concealed (and/or loaded) firearm available to those aged 18 to 21 on a nearly identical basis as is available to persons 21 years and older. In order to avoid risking loss of recognition of our current carry permit, the permit for 18 to 21 year olds is a different permit, known as a provisional permit to carry a concealed firearm. West Virginia did this last year and had zero effect on recognition of their regular permit. They actually ended up getting several States to recognize their provisional permit.
Other States will be free to recognize or not recognize our provisional permit entirely independently of whether they choose to recognize our regular permit. The provisional permit expires on the holder's 21st birthday when he is eligible for a regular permit. (There may need to be a little cleanup here later to make sure nobody with a provisional permit is left without the ability to legally carry while their regular permit is issued.)
The one difference between the Provisional and regular permit is that those with a Provisional permit cannot legally carry onto the grounds of nor into buildings of any K-12 school. This is obviously intended to avoid 18 year old high school seniors from carrying a gun to high school. There is no 1000' exclusion rule. I do not know yet how this will interplay with the federal GFSZ law.
Charles