While GCC 7 feature development has ended, Red Hat's Jakub Jelinek wrote in this latest GCC status report, "Patches posted early enough during Stage 1 and not yet fully reviewed may still get in early in Stage 3. Please make sure to ping them soon enough."
GCC 7 development code currently has four P1 regressions (the highest priority), 114 P2 regressions, and 177 P3 regressions along with more than one hundred more P4/P5 regressions.
GCC 7.1 will be the first stable release of GCC 7 and is due out in early 2017. More details on GCC 7 features and compiler benchmarks will be posted on Phoronix in the weeks ahead.