Yes, it’s true. Nothing is etched in stone for J.T. Miller, a Ranger for two games, or for Chris Kreider, either, for that matter. But if these two Yoots of America — OK, Youths — can not only maintain roster spots and coach John Tortorella’s trust, then the Rangers could present a triple-threat offensive line balance that seemed unattainable a week ago given the construction of the roster. Change is inevitable over the course of a season, but the line combinations fashioned by Tortorella for Thursday’s 4-1 victory over the Islanders that will all but certainly remain intact for tonight’s Garden match against the Lightning created a dramatic change to the Blueshirts’ previously unbalanced look. Breaking up the Big Dog Line that featured Brad Richards between Marian Gaborik and Rick Nash and that played as a unit with the Marc Staal-Michael Del Zotto defense tandem — The Rushin’ Five, if you will — was the first step.