I still contend that price cuts being fewer in number and lesser in degree than they were in Gen 6 & earlier is why PlayStation & Xbox systems are able to run on longer generations than the previous norms. Last generation it appears to be the culprit behind slow growth and delayed peaks. Essentially, last generation was as long as it was on purpose, and probably for good reason (imagine how much weaker the PS4 & XBO would have been at $400 had they launched in, say, 2011).

This generation, it's basically been keeping non-holiday sales steady, but not producing any clear longer-term growth, with official short-term holiday price cuts diverting a larger portion of sales towards Q4 than in prior generations. Outside of Nintendo systems, you don't see the early peaks you used to anymore, and it remains to be seen if even Nintendo will still run on shorter gens than Sony & MS, or if they too will attempt to put the Switch's sales on a PS/Xbox-style "slow burn" sales trajectory.

The chart is showing official MSRP (Manufacturer's Suggested Retail Price) for the consoles from what I can tell. The XB1 and PS4 SKU's you see that are selling for less than $300 right now are mainly discontinued SKU's or SKU's that are discounted temporarily by the retailer. The official price for both XB1 S and PS4 Slim right now is $300. Hopefully Sony and MS both officially drop to $250 or $200 soon. 

As someone else said, these 500GB consoles are still very popular and in stock and have been selling for less than $300 for months. And as others have pointed out, Xbone has been less than that price for awhile now too.

Hell when I saw this thread and checked Sonys own website they still were linking to Walmart and the 500GB SKU.

Yeah, I think this is a factor too.  There are several factors. 

Although I'm still not convinced Sony will release the PS5 after 2019.  One reason that the last generation was so long was because Sony backed themselves into a corner by making the PS3 so powerful (and consequently really expensive).  IIRC correctly, the PS3 came down to $400 in 2008.  So that is only a 5 year gap between the PS3 at $400 and PS4 launch of $400 in 2013.  Once you account for the huge price of the PS3, it actually didn't take them an unusually long time to release PS4.  The unusual part was actually the high power of the PS3 when it was first released.