In my opinion a new race is highly possible but much much more highly improbable. The ship to incorporate the new race into the Zhaitan arc has long since sailed and has been sunk by Bubbles.
Tengus? Oh, they’ve been around. Their archievement in the personal story? Shooting arrows at hapless survivors in LA during the Scarlet attacks and rudely threatening other races, an instant favorite.
I don’t see them being introduced in other expansions either. Nor do I see ANET taking on the hassle of splitting each story into new/old races. Also the arguments of the tons of armor sets which would have to be retrofit to the race weigh heavily. So a new race would have to use the skeleton of an old one. I for once wouldn’t be interested in a Norn with an ice bear head.
Also I doubt it is what GW2 needs. I would be far more interested in new classes/skills/elite specializations.
But I’ve been wrong before. If ANET finds a way to make it possible without using too many resources on it I hope you’ll get the race you want. I would play a skritt