No. Sean, the original son born pre war will always die if you progress to the end of the story. Either he dies when you destroy the Institute, you kill him yourself, or if you side with the Institute then he dies from his illness.
Siding with the Institute will pit you against both the Railroad and the Brotherhood of Steel factions. The Minutemen, of course, are spared from the Institute's wrath. The Institute needs an new leader, and you're in need of a nuclear family.
MatsuriThe Couple. GaaMatsu (我愛マツ GaaMatsu) is the term used to refer to the romantic relationship between Gaara and Matsuri.
In fact, some of those Jinchuuriki were used as Edo Tensei summons from the dead during the Fourth Shinobi World War that concludes the series. But, Shukaku's jinchuuriki is still alive, thanks to Chiyo giving her life to resurrect Gaara.
Gaara has dark circles around his eyes because shukaku will not let him sleep, because Gaara will lose Control if he does sleep.