FF7R is a sequel so it isn't retconning anything. I'm so glad this is the case, because the first thing I heard about it was that Shinra blew up its own Mako reactor instead of Avalanche, which I took to be a shameless attempt to wipe the blood off Barrette's hands that would untimely undermine his character arc later on. 

Now, though? I'm just gonna sit back and enjoy Nomura's Wild Ride.