Combined Traits?
Dueling already has mantras, so if manipulations would be merged they would likely be in chaos.
WvW Roaming with Mesmer
Glamour mastery and temporal enchanter will likely be merged. (based off of the new cantrip mastery or vital striking aquamancer merge). Shattered conditions & vigour on shatter will probably get merged. Or heal on shatter.
Traits like halting strike could be merged with power block or confounding suggestions for a new grandmaster. Or maybe power block/confounding into 1 trait. Illusion of vulnerability/halting strike could be another combo. Halting BLOCK!
Clone death traits could maybe go for a merge. Even though in 3 different traitlines, I think this will happen.
Mantras… 3 charges and shorter CD into one? Seems like a decent mantra mastery. 4% more damage per mantra is a good PvE choice but boring trait. I hope it just gets buffed some other way. Restorative mantra and disrupters sustainment; I want this combo to work somehow with a mantra build that interrupts while charging other mantras. Currently, the base heal is too strong and scaling too weak though. Since stability has been changed, maybe a rework or buff to protected mantras to give it stability. So a bunker that gains armor/stability while charging mantras. Heals after charging mantras and if interrupting while charging (F3/MoD) will get a bigger burst heal.