For those savvy tech gamers who wait for deals or have great deals available, it's been possible to get $200-249 R9 290, $255-280 R9 290X and $230-245 R9 390 for months, even years for R9 290 series. That means for these gamers Polaris 10 shouldn't matter. In reality it shouldn't either way because it would be akin to upgrading from a 6950/6970 to say a 7850/7870. The proper upgrade for higher end level chips such as Hawaii is Vega. At the same time, prices will reflect all of the above. Polaris 10 won't be a $550-650 product.
Also, look at regular MSRP and prices worldwide. Most of the world doesn't have these deals. Right now for AMD they are officially selling 390 for $329 and 390X for $429. If AMD beings Polaris 10 to $179-249 price levels, that's a massive improvement from what the rest of the world has. Look at how many people on Steam have 960 and those cards sold for $180-220 for almost all of 2015 and for most of the 2016 until now. Imagine getting 390X performance for $249, then with rebates it could be $220-230. That's easily a 70-80% improvement over a 960 as far as GPU power goes. Look how well 960 sold and that card was overpriced trash. Getting 70-80% performance for these gamers is a big deal given how weak the $200-249 market segment is. Finally look at where the competition has 390X level of performance. 980 generally sells at $420-460 levels. Bringing that to $249 MSRP is a huge improvement, miles better than 960 replacing a 760.