I'm really not sure about the timelines, but I can easily speak to the state of things for today: LLMs are very wasteful and slow for real-time decisions. The "thinking" ones have no chance and if you disable thinking, they really struggle with querying the context with the right calls. For the once in a moonshot scenarios that they have enough context and ample time to react, they are great!

Developing AI scripts, however? They are crazy good! I try to re-balance the game to give a little edge to the humans, then it takes a single iteration for your not-even-sota LLM to destroy me. I mean I'm not the fastest RTS player but for the lack of skill, I have the advantage of being the designer of the game :)

About the RA2 AI scripts: You can react to enemy faction, composition etc. but it's impossible to program it to pull back its tesla tanks when they are under threat from a bunch of rocketeers. Those things are hard-coded in the game engine. I think the only exception was the DeeZire mod which patched the game exe, if I'm not hallucinating.