"Gamestudio could compete with unity just by making a more powerfull game engine"
Well yeah , Gamestudio could beat Unity if it were to release A8 and it were some kind of beast full of new and handy features that would make Unity feel outdated. Only problem is , Unity did that exact same thing to Gamestudio a couple of years ago , and now it has given it's indie version for free , obliterating most of the current competition (I would say all), a very strategic and smart move by Unity I would say.

But could Gamestudio stay competitive with A8 ? Of course.
Do I think it will ? Of course not.
Is Unity the new king of indie engines ? In my opinion , definitely , for the time being at least , as no one knows what the future will bring.