At a conceptual level, it makes 100% sense that companies are moving away from bespoke engines and towards a standardized engine. This is something you see in many different industries. Spending a whole bunch of money and effort when 95% of your requirements are the same as everyone else is a bit silly.

However, you’re completely right that there’s the same danger as in other industries where the ‘boring software infrastructure’ gets standardized and outsourced: a niche monopoly able to exploit their position. What tends to happen in the long run is an open source project for that infrastructure run by an NGO with the industry members (in this case AAA game companies) on the board of directors.