Before the official announcement Polaris 10 was heavily rumored to use just 110-135w of power. I get the feeling that AMD got a bit generous with their official TDP rating, I doubt it actually uses close to 150w, but I guess we'll see when the reviews start coming in later this month.

For what it's worth, the 7850 that PS4's GPU was based on was a 130w chip. 20w isn't that big of difference, MS would simply need a roomy case and a 120mm cooling fan, much like Xbox One's case and fan/heatsink. It's also worth noting that Xbox Scorpio may be using AMD's new 14nm Zen CPU architecture, so it's possible that MS could make up the difference with a lower thermal rating for the CPU part of the APU. At the very least I think MS will hit 5 tflops next year, maybe higher.

$399.99 will be easy. 

This is cheaper than the 7850-7870 GPUs that the PS4/XB1 used for their time (7870 was $350 when it launched in mid-2012). 

To be honest looking at that Polaris 11 price, Nintendo really dun fucked up by not using that chip (it seems). $130 retail for a 2.5 TFLOP GPU at under 50 watts?

Well, the 460 is less than $140 at retail, which means Nintendo could likely get a custom APU (CPU+GPU) using a Polaris 11 derived GPU for less than $140 since they'd be buying in bulk. I think Nintendo could definitely hit $250 if they wanted to, maybe less. The main concern is the controller, if it has a screen again it will raise the price some.

Any confirmation of that or is it just a rumor?

I think that $249 needs to be the absolute ceiling for NX pricing. Hopefully they don't go overboard with the controller concept.

Also interesting is the R7 460 specs leak. 2.5 teraflops for less than $130. Some rumors have suggested that NX will use Polaris 11. 2.5 teraflops for less than $130 at retail could potentially allow Nintendo to top PS4 specs for $300 or less at release.

Sony hasn't said anything about the Neo. But based on the leak, an October release seems likely since all games that release after September must have both PS4 and Neo versions.

I'm sure MS can get around that issue by keeping the esRAM for backward compatibility purposes and combining it with much faster GDDR5 instead of XB1's slower DDR3, but I'm no expert. I'm sure that MS has a solution in mind to have both good specs and backwards compatibility, according to the sources that leaked Scorpio's existence, Microsoft's top goal for Scorpio is beating Sony in the specs department because they're sick of getting inferior 3rd party ports.

I can't see Nintendo hitting 4 tflops for $250 in March. Neo is 4 tflops and it's rumored to be releasing at $400-450 later this year. I do think Nintendo will aim to beat PS4, but at this point I'm doubtful that they'll try to match Neo. Something like 2.5-3 tflops for $250-300 is what I'm expecting. Since PS4 has at least 3 more years of support ahead of it thanks to the clause that requires devs to keep supporting PS4, as long as NX beats PS4 specs and is x86 for easy porting, Nintendo should be able to get 3rd party support. Then once PS4 support is dropped, Nintendo could theoretically use those Supplemental Computing Devices they patented to boost NX up to Neo/Scorpio level to keep getting support.