They are already working on Heroes Online.

Are we talking about that free-to-play browser game that was announced recently? If so, then it's, at the very least, not a serious attempt. Heroes Kingdoms didn't kill Heroes. And Heroes Online won't kill it either.

The fact that they are releasing a Gold Edition with the second DLC right away raises some concerns.

The exact same situation happened with Civilization 5. First, a buggy original was released. Then, monthly patches with periodic DLCs. Then, a Gold Edition was released, which included all the released DLCs. And soon after, a full-fledged expansion was released.

Let's not forget that there can also be a Platinum Edition.