"First off, I don't think the strategy genre is anywhere near the 'brink of extinction'. It's still going strong with plenty of new titles coming out every year. Sure, maybe some of the more complex real-time strategies aren't as popular as they used to be, but that doesn't mean the entire genre is doomed.
As for saving it from potential decline in the future, I think there are a few things game developers could focus on:
Making the games more accessible to casual players without dumbing them down too much. This means having clear tutorials and progression systems that guide new players through the basics while still offering depth and challenge for veterans.
Experimenting with new gameplay mechanics and modes that shake up the traditional formula in interesting ways. This could mean anything from introducing asymmetrical multiplayer to trying out different genres (like stealth or survival) as part of the core strategy experience.
Being more transparent about DLC practices and avoiding pay-to-win situations that make players feel like they have to shell out extra cash just to keep up with others. This goes for both microtransactions and premium expansions.
Emphasizing social features and competitive play options that give players a sense of connection and achievement beyond simply playing through the single-player campaign on their own.
Leveraging modern technology (like better AI, more dynamic environments, etc.) to create richer, more engaging experiences that feel fresh and exciting even for longtime fans of the genre.