You're forgetting  Horizon !

I think hardware refreshes will have a smaller impact than they did last generation. The 360 & PS3 both had a lot more room to grow when their Slim models came out. As of the end of November, the PS4 & XBO were at at least 15.96M and 14.34M respectively in the U.S. At the same point in their lives, the 360 was at 12.42M and the PS3 was only at 9.76M. And recall that the 360 had a commanding share of the Xbox-PlayStation split in the U.S. (as of the end of 2015 the split was 61.67%/ of the market share for conventional 7th-gen consoles). The comparison is a bit iffy since the 360 came out a year before the PS3, but still, even though the race was a runaway for the 360, at the same time the 360 was not selling nearly as quickly as the PS4 & XBO are. Even with slightly less than half of the market share for conventional consoles, the XBO has still managed to outpace the 360 for most of the past 3 years. And the PS4 is the third fastest-selling console ever in the U.S. after the PS2 & Wii.

One of the main reasons last generation lasted so long was because of slow growth for the 360 & PS3. They didn't peak until 2011, and the PS3's peak was not pronounced (the PS3 was up only 4.4% in 2011, and 2010 was nearly perfectly flat from 2009). Because of their slow growth, and therefore larger room for future growth, the Slim models provided a much stronger boost for sales. The 360 & PS3's slow growth can at least in part be explained by them having higher inflation-adjusted prices both at launch and at any given point in their lives than other major consoles that preceded them. The 360 also had the RROD issues, which may have stymied growth (the 360's sales were roughly flat in the U.S. from 2006-09, not growing appreciably until the 360S was released). So, when slimline models were released, they caused a much bigger spike in sales. The PS2's sales may corroborate this hypothesis, as it experience huge growth after a proportionally very large price cut, and because of its massive market share it was already sitting at over 22 million units and the end of 2003, and by time it got its own slim model it was already at over 25 million; it had clearly passed the point where any future growth was impossible.

PS4 & XBO sales may see a slight uptick this year, but I don't think we'll see much growth, and sales will almost certainly start to enter the terminal decline phase in 2018. Much like the Pro, the Scorpio will have a minimal impact on sales. They're more like the DSi and New 3DS than the PS3 Slim and 360S in terms of effect on sales.

It would have made zero differnce.

Consumers are too smart these days, and it was kinda obvious this was a turd.... them polishing it up, would just have been them throwing away money.

Tell that to those buying the OG PS4 over PS4 with UC4.

In all fairness the OG is $15 cheaper and some might prefer the old aesthetics.