The Qt 5.4 feature freeze is coming as planned. Qt developers hope to do an alpha release next week (14 August), a beta release on 4 September, release candidate on 2 October, and the final release on 23 October. Of course, with Qt releases the schedule is subject to change pending any last minute bugs, etc, as with all Qt5 updates thus far the official releases have ended up slipping by about one month.
Some of the Qt 5.4 features include improved support for OpenGL ES 3.0/3.1, QImage now supports 10-bit per color channel images, QQuickRenderControl is now public to allow efficient rendering of Qt Quick 2 scenes into FBOs, Qt Bluetooth now supports BlueZ 5 and Bluetooth Low-Energy, the QtWebEngine component is a new module of a web rendering engine based on Chromium, QtWebKit supports an OpenGL-accelerated 2D canvas, QtWebChannel to provide better integration between web technologies and browser engines, improvements to HiDPI support, and there's many other developer changes. A brief listing of the changes can be found via the Qt Wiki.
Notice of Qt 5.4 being under a feature freeze was posted to the Qt development list. In case you missed the news from earlier in the week, Digia is spinning off its Qt work into its own business with signs of those changes coming later this year.