Human history changed forever!
To the people of the Milky Way, the Age of Mechs continued to prosper like always. Their race maintained a dominant position in their home galaxy.
Sure, the Red Ocean and all of the manpower and assets invested into it had disappeared, but the loss did not result in a drastic weakening of human civilization.
At most, human civilization was set back by a century or so. It would probably take at least that much time for society to compensate for all of the warships, Star Designers and god pilots.
Perhaps all of the relatives of the missing colonists of the Red Ocean may mourn for the loss of contact, but life eventually had to go on. New families would arise over time while the impact of the people that had gone missing would continually fade over time.