There are a few things I can go back and add, so probably will soon. And no, I don't know anything about the game's future.

I have actually got a few epic cards from the gold summon, even though it does not mention the possibility. However, this summon should be used sparingly because of the fact that gold is actually not so common of a resource once you have made some progress.

Other games only gives you one card per summon, though, while this one gives 6 for about the same price. So at least there is that.