The key for success for anyone in any competitive market is to find a niche and fill it well. I think that the engine market is big enough for several players. Game Studio just needs a bit of tuning to a niche left open by other engine makers. My opinion is that it's the template system. I know seasoned programmers will say, bah, but a robust FPS or RPG template would probably do wonders to generate revenue from enthusiasts.

Making a spectacular game to showcase the engine and generate revenue would be wise as well.