Piece of advice, free of charge: Players who play at the top level, and who would grind on-demand queues against each other, care very little or not at all about cosmetics. You won't get anywhere with alternate art coins that we see for 3s every 40min. I hope that the battleboard and the coin skin are just the easiest to talk about and that the rest are things your best players actually want. Because most of them are already at the door.
not issue if coins are tradable.
Anyway, I'll restrain myself from posting more until we know the full extend of items purchaseable with Cosmic Coins and Siege Sacks.
By the way, dear HXE team, I don't think you'll get away with "For starters Cosmic Coins will be used to purchase X but in time we hope to introduce more outlets" for this one. Because we have experience of the possible extend of what "in time" really means.