With the only major change in the PS4 Slim being the size of the console, and with the more extensively upgraded PS4 Pro debuting this month, it appears gamers largely chose to ignore the new version of the PS4.
On the other hand, Microsoft reduced the footprint of the Xbox One console and added HDR gaming just like the PS4 Slim, along with the ability to upscale games to 4K and playback Ultra HD Blu-ray discs. This made the Xbox One S one of the cheapest UHD 4K players on the market, even without considering its main gaming features.
And Microsoft was able to do all of this, plus offer a modest performance upgrade for existing games, at the same price point as the PS4 Slim, $299.
Sony has already released the powerful PS4 Pro, which is very powerful but costs $399. Its success will be evaluated in the November sales results. The PS4 Pro will have some games available in native 4K, but most upscaled, but in a more advanced way.