Only time can tell us that. 5.0 will perhaps bring us some new innovations that'll keep the common folk happy until the next set of updates roll through. Hairs and 3d Objects seemed to be quite the addition looking back on it.
Though while trying to keep the game away from a pay to win aura, that hampers some things from making the community better. There's always room for improvement, and I'm sure the Devs will continue to find proper ways to keep us all happy.
To answer your question, I believe Toribash has always been going up. However the changes haven't been extremely large or dynamic. Despite that, Toribash itself is Unique, just find ways to change the game for yourself. I'm sure as you spend more time on the game and actually take in the changes that occur, you'll realize TB expands at a decent rate every year.