Did a few characters die? Yeah, 4-ish. Cannonball, Jubilee, Prodigy, Dazzler (maybe - some level of self-resurrection previously established). Iceman? Nope. Jean? Probably not. And the aforementioned cannon fodder will pop up as soon as the Five are back “online”.
The whole “massacre” angle is coming from Xavier arrogantly assuming all the gate-walkers are dead just because HE can’t hear them.
I get the theme, the X-Office has been recycling all the old crossover titles. But, this wasn’t close to a massacre.