Intrigued by the topic, I asked Google directly whether a future version—like a hypothetical "ChatGPT 7"—could rework a game engine, such as the one used for Supreme Commander. It replied that this would be possible, provided it worked in stages alongside a team of developers—and that it could be done relatively quickly.
When I posed the same question regarding version 8, Google responded that it would be feasible, requiring only a single developer, and that the AI could handle the task quite rapidly.
Consequently, the potential absence of source code—which the current rights holders might not even possess—will likely prove to be only a minor obstacle in the near future.