It seems that at least all new stuff in Max will be QT and will get the updated GUI style from now on as seen with the newest modifiers: Chamfer, Data Channel, Path deform etc. or the new updated parts of Max UI like the new Hotkey Editor. A very nice develops regarding the new UI style can be seen in some leaked screenshots concerning mainly the new AOV Manager and Bake to Texture manager. Also the new Retopo Modifier seems to share the style of the new modifiers as expected. Don't keep this new style only for the new stuff ! this will only add to the countless UI inconsistencies in Max. Start to update the other modifiers and the rest of the UI with this new style !
New Modifiers (on the left the new Retopo Modifier preview)

New and old menu style

Previewed Updates (AOV manager, Bake to Texture)

Video sources
1:40 (Retopo Modifier)
at 1:00 AOV manager, at 5:40 Bake to Texture