What happens to the members of W.I.S.E. near the end of the Psyren?
If you look at chapter 145 (page 4) in the manga, you can see this:



Yoshina asks No. 7 about Ouroboros, and she says that it has disappeared into space again in exchange for her brother's and Grana's lives.

So, if we take the words of No. 7 seriously, yes, they died.