Future expansions.

The patch delay means that Black Hole has stepped away from the project, and Ubisoft is looking for a replacement. Why? Because, as you say, Ubisoft is creating Heroes 6 just to tick a box, without any passion, and they've already made a profit, so why would they fix the game and spend money on a new developer? It doesn't make sense.

Everything adds up. They're looking for a replacement to continue making money. They're getting some profit from the series, even if it's small. The question is, how are they getting it?

All the innovative solutions were invented by Ubisoft. It doesn't seem like they're just doing it "to tick a box."

All the innovative solutions are aimed at simplifying the game. Of course, they're targeting the masses, trying to attract new consumers.

So why doesn't Ubisoft just make an expansion pack instead of patching the original? Because Ubisoft isn't completely indifferent to Heroes.

They're patching the original to avoid losing customers completely. An expansion pack is a sure way to get a little more money out of us.

The story is impressive and has a continuation.

Impressive? That's a matter of taste. Has a continuation? Obviously, yes, the ending seems to hint at that.

Besides, why would they abandon the brand they bought if they can still milk it, and quite well at that? They're not fools, and they won't miss out on their profits. They'll continue to hire small companies and follow the same path.