Future expansions.

What are your predictions and suggestions?

The Academy will definitely be released much earlier and as DLC: they simply didn't have time to integrate it into the game before the release. It's not a given that there will be such a long gap between the original game and the expansions. You yourself noted that Hammers of Fate was released a couple of months after the original Heroes 5. I think it will take about six months or less for the expansion to be released.