According to CanonRumors, Canon will announce the EOS M3 successor EOS M5 late this year, probably before CES 2017. Also a new EF-M lens EF-M 18-150mm f/3.5-6.3 IS lens will be announced together.
The new EOS M5 will be slight up market than EOS M3. It will be an APS-C sensor mirrorless camera. There is no rumors on DPAF or 4K for EOS M5. Don’t expect big ergonomic changes.