The new classifications would take effect in the 2017-2018 school year, and may go through several revisions between now and then.
Every 4 years, the NCHSAA evaluates the population of each member school and realigns its classifications and conferences. The current realignment process began this fall, but the change won't take effect until August of 2017. The first stage of the process is complete, as the NCHSAA released proposed new classifications and conferences in late 2015.
One new aspect of the current realignment is the NCHSAA's use of a "20-30-30-20" model to determine the classifications. Rather than dividing schools into 4 roughly equal classes as in the past, the NCHSAA decided to put the smallest 20% of schools in 1A and the largest 20% of schools in 4A, with the 2A and 3A classifications each getting 30% of the total number of schools. This will significantly reduce the number of 4A schools, raising the smallest 4A school from 1368 in the 2013-2014 school year to 1656 in the new proposal.
During the next stage of the realignment, the NCHSAA will take appeals from schools that wish to change classification from the current proposal. That two-tiered process will progress through the spring, when the realignment will be finalized. There is still one school year remaining on the current alignment, though, and the proposed changes would take place in the 2017-2018 school year.