I'd be willing to bet that, had it been released at that time, at least one of the songs would've become a perennial Xmas standard. Not sure which one, though.
My money would be on "Morning Christmas". Such a dynamic, magical-sounding song, perfectly capturing the powerful and awe-evoking emotions of wonder felt by children waking up on Christmas day.
Or something like that.
I think, far and away, that Morning Christmas is the best of the 70s Xmas songs. But, is that the one that would've been released? I would hope so.