Giving it some thought, Sony does have a bit of a problem on its hands here.
While this and last week can be handwaved away as the "FIFA" effect, the fact still remains that they haven't and aren't giving people enough reason to upgrade to the slim and pro.
Unlike the one S, there is no clear visual improvement in looks in the slim and the PS4 OG is "Good enough" for most people's needs. This weeks firesale is obviously a responce to that, but the problem remains that going into the holiday season, there is no real reason to buy a PS4 if you haven't already.
The slim is just not an exciting product. It's meh at best.
Now the pro on the other hand, has a clear tangible difference, but to see the full benefits requires a television purchase that many aren't ready or willing to make yet. 4k is gaining steam, but for this year, for this Hoilday season it's not enough, especially as the most distinct advantage of a 4k device has been omitted.
Let me be clear, I really think the "Microsoft is back" cries from here and across the pond are premature and pretty much fueled by fanboy wishful thinking, but Looking past Hoilday 2016, Sony is going to have a hell of a job keeping up their momentum, especially as it seems for the past 6 months they are running on interia which itself is running on fumes.
The big wild card in all of this is PSVR. If it connects with a causal audience, none of this will matter. But I'm flatly unconvinced that it will do anymore than a decent start out the gate and then a slow decline after.
The thing to take away from all is the fact that Sony so far has squandered what should have been an insurmountable lead in sales, marketshare and influence in the industry and while this generation is still pretty much wrapped up, they have give Microsoft enough of a opening to turn the tables in a few years time.