You were on fire there until the end. Before then you carefully noted that Morrissey's problems were largely "commercial". But then you had to mention his legacy.
His legacy will survive untarnished no matter how poorly the sales numbers look. Do not worry.
The problem with sales figures is not the impact on the legacy. It's the effect they have on being able to release new material.
YOR's sales have been pretty disastrous. There is a chance the album can be rescued but only really if subsequent singles receive tons of airplay, or the album does well in the Mercury or BRIT awards; all these eventualities are unlikely but not impossible!
If YOR doesn't recover, it's pretty unlikely that a conventional record company will offer Moz a deal he considers acceptable, and he could ffind himself back in the (metaphorical) wilderness.