I would not swear on a stack of Tal'Dorei Campaign Settings that there is no way that Vax comes back in mortal form, though I would admittedly find it to be pretty abysmal storytelling. That isn't important though; what's important is we just had Deanna and FRIDA and their extremely complicated feelings about being resurrected after centuries, and they both died relatively normal and came back normal. I think any story in which Vax comes back mortal is a horror story.