The current schedule puts the alpha freeze / software string freeze / change checkpoint on 16 February, Fedora 24 Alpha on 1 March, Fedora 24 Beta on 12 April, and the final release on 17 May. However, a proposal being pushed to the Fedora Engineering and Steering Committee would end up pushing back all of the F24 milestones by a few weeks: up to three or four weeks.
The call for re-evaluating the Fedora 24 schedule is being done so that there would be time to do a mass rebuild of all packages. With the current schedule, no mass rebuild was scheduled. Rebuilding all of the packages would be done so that they could be freshly built under GCC 6 to avoid any compiler woes. The original plan was to just selectively rebuild the necessary packages under GCC 6 once this major compiler update plans but for the rest of the package archive to remain built against the existing GCC 5 based compiler.
While GCC 6 won't be officially released until March or later, the plan has been to get the current GCC 6 compiler snapshot into the Fedora 24 repository by end of January. GCC 6 is surely going to be in Fedora 24, it's just a matter of whether a full rebuild happens or not. However, based upon this FESCo ticket, the schedule is being re-evaluated and I'd be willing to bet they'll go in favor of pushing back the F24 schedule to let the mass rebuild take place.
A comment on the ticket also points out that new strlcpy and strlcat functions are being added to Glibc, which will likely be in v2.23 that in turn is planned for Fedora 24. These changes to Glibc could also cause failures and would be another reason for rebuilding the F24 package set.
FESCo should decide soon on this matter. The current proposal would be pushing back the entire Fedora 24 schedule by two to three weeks, which would end up likely making F24 release in June. The good news is that pushing back the schedule now would also allow a few more weeks until the change checkpoint deadline to let more features flow into this next release.