I frankly do not believe Sony has to do much in response to this. While the Scorpio will be significantly more powerful than PS4 and PS4 Pro, it will also probably end up costing about $100-$200 more than the PS4 Pro. In addition, PS4 and PS4 Pro have a more diverse game library (pretty much the same multiplats on both systems, PS4 has more exclusives and more games from Asia), so I do not see the Scorpio being a threat to the overall PS4 platform/eco-system (unless MS decides to add more to and diversify their exclusives library in order to better compete in Europe and Asia). In addition, if you care only about multiplats and want a stationary system, then the power to price relationship is pretty much linear (XOne costs the least and has the least power, PS4 Slim is next, followed by PS4 Pro, followed by Scorpio which will probably end up costing more with the most power), so we are not most likely going to be in a situation where Scorpio and PS4 Pro compete at the same price.
On top of everything, Scorpio, like the PS4 Pro, is a mid-generation upgrade. As such, there is no game exclusivity for this system, hence most regular consumers that do not have 4K TVs (and I am not talking about enthusiasts, who tend to be most vocal) will most likely be satisfied playing the current library at lower resolutions and potentially lower FPS.
Don't get more wrong, the Scorpio is doing what MS wants it to do. It will breathe more life into the XOne ecosystem, MS will most likely be able to sell it as a more premium system and hence have a higher profit margin on it, and they will have an option for those buying 4K TVs (where adoption rates are increasing right now; source: https://venturebeat.com/2016/09/19/4k-uhd-tvs-are-being-adopted-faster-than-hdtvs/ ) and early VR adopters (which is a relatively small group, and will most likely not be a major sales force; unless MS creates a much more affordable VR solution for Scorpio).