I'll set aside the.. critique of the correction and highlight the main relevant point from that : connecting to the discussion from LordGigaIce et al, Generations has been the general label for the collector-aimed portion of the line since at least AOE. That line had the same overall name and packaging style for everything (since that's where they debuted it, giant red rotated-90° TRANSFORMERS logo and all), but the stuff that wasn't one-steps and whatnot was flagged as "Generations".
I guess the whole Generations thing can be summed up on my end like this...
Up until AotP both Studio Series and whatever the Generations line was, had Generations logos on the packaging. They were both categorized as Generations product by Hasbro and retailers. And still are today, even with the Generations logos being taken off the boxes.
So "the line isn't called Generations, it's just an umbrella term" seems like a distinction without a difference to me.
As far as Hasbro, Walmart, Target, etc... are concerned, Studio Series and AotP are all "Generations," so however you wanna define that, it seems like it's one line.
Cordoning off part of that line as "Studio Series" seems like an informal division within Hasbro to give movie stuff its own space within Generations rather than being a totally distinct line.
While Hasbro has played fast and loose with lines to slip in things they couldn't fit elsewhere before, I don't think that's happening with SS and Generations today. It all seems to be one big "Generations" line, just with different sub-labels.
So I don't think Hasbro can be accused of playing fast and loose with retailers in this instance, because it's likely all Generations slots anyway. Take away the sub-labels and you have the same number of slots at retail.
Hasbro deciding to redefine the distinction between SS and the rest of Generations after that distinction got muddied shows that they see value in multiple flavours of Generations product at once, but I don't think retailers particularly care about that outside of how well it sells.