Lars Knoll sent out a notice this week to inform developers they are planning for the 5.7 feature freeze next Monday, 1 February. So far being approved for still landing past the feature freeze is printing support for the Qt Web Engine, BTLE support for Linux, and modules that are flagged as being a technical preview for Qt 5.7.
Qt 5.7 is expected to bring many Qt WebEngine improvements with its base off Chromium 48~49, support for NVIDIA DRIVE CX boards, Quick Controls 2 improvements, Qt Script is now deprecated, and there is work on the Qt Speech and Qt Wayland technology preview modules. Details on the upcoming Qt 5.7 features can be found via this Wiki page.
Originally Qt 5.7 was supposed to go into its feature freeze in December with a release in April while the latest release plan has the feature freeze next week, Qt 5.7 Alpha on 23 February, Qt 5.7 Beta on 31 March, and the Qt 5.7 official release on 26 May.