Originally I liked the concept of tinkerers. I had previously liked the GW2 engineers. That said, the blind devotion to the exclusion of all other ideas that some of the tinkerer advocates have had over the past while has really killed the concept for me, and now I'd rather not see them.
What I'd like to see now is an idea based off something someone else brought up: Dragon Knights. My idea on this:
Theme would be similar to the spartan/amazon look.
Would wear mail armor (scales on a dragon)
Shield + pole arm (spear), similar to old Titan grip off tank setup from a couple expansions back
Specs:
Tank - used bronze flight abilities to slow/delay enemy attacks, and rewind damage taken
Melee dps - bring back a bit of the gladiator style from warriors, and add draconic styled magic
Ranged dps - blue flight empowered spear throwing
Add in some dragon styled abilities like teleporting through the emerald dream for mobility, sleep as cc from the green flight. Maybe some earth/magma based defensive cooldowns from black flight.
Would fit in with whatever might be going on with Chromie.
Variation: replace melee dps with a red flight based healing spec since we have lots of melee already.