Interesting development. We learned a few things. First of all, Tim Sweeney and Epic are no longer neutral in the competition between the console manufacturers for market dominance. By accepting this deal, they have tied their financial well-being to Sony's. It's now in their direct interest for the PS5 to be as successful as possible so their new shareholder will be content and not interfere with any other goals they have and it's in Sony's interest for Fortnite and the UE tech to be as widely adopted as possible. None of that is illegal or dishonest except the part where Tim Sweeney was calling the PS5 revolutionary and comparing it to high end PCs at the same time that he was negotiating to raise as much capital from them as possible. I don't know what that did to the share price of each company but it vaguely sounds to me like something that the Consumer protection agency and even the SEC may want to review.
It also raises the question of where that leaves Microsoft which was probably already a bigger client of Epic than Sony before all this (as far game engine tech is concerned). If I'm Phil Spencer, beyond the raw economics of it which I have analysed above, I can no longer view Epic and Tim Sweeney as a trustworthy partner or supplier. The fact that XGS has enormous reliance on the Unreal Engine is a weakness for Microsoft as of today, no matter how nice Hellblade or the next Obsidian RPG look. You can no longer blindly assume that you are getting the best that the engine can offer for your money and also you are partly making your competitor more successful just by running your business. This is something that you do when you don't have a choice (MS using Blu ray, Sony using Azure) but not when you do. It's exactly why Sony did everything they could to have Amazon as their cloud infrastructure partner before turning to Microsoft.
The logical effect of this is XGS should start exploring and if possible adopting alternatives to UE. Some of the disadvantages of those alternatives now are offset by the fact that they are reducing Xbox's reliance on Epic and this warrants a complete reconsideration. If that Slipspace engine has really costed as much as it is rumored to develop, may be it is up to the task and you start spreading its adoption in order to diversify ASAP. Just my 2 cents.