Best reply so far:
Basically barring an unforeseen catastrophe that necessitates an additional character wipe, character data from phase 4 will transfer to launch (except pvp data). The one thing that to my knowledge has not been answered however is whether characters that were newly created during phase 4 will be restricted to the same subset of servers that 1.0 characters are currently going to be restricted to.
So as of right now, I'm not sure what happens to new characters. Hopefully I can find it or they address it soon.