I think the focus on Acedemy and Battlegrounds were business mistakes.
Not really. The idea behind these new game modes was/is solid. Unfortunately, for my taste Academy is too different from Arena to serve as a useful introduction. I still have high hopes for Battlegrounds to replace the standard Arena mode, though.
Simply churning out mage after mage without changing anything about the basic (Arena) rules would have done nothing to grow the player base. Very high, and continously increasing complexity due to a fast growing glossary and game length prevent the game from becoming more popular.
I'm not sure if the situation we're currently in is much better, but it was worth a try.
The problem is that the diversification has lead to resources being spread too thin. Arcane Wonders is too small a company to churn out new products for three (closely-related, but still) different game lines at the same time with the same speed as for a single game line.
And commercially it wouldn't have been a good idea to do so, either. Mage Wars is, and probably always will be too niche.