Only those that find a Ritual Stone in their Dungeon ventures will be able to sacrifice their Settler and receive the underlying Shard Value. The drop rate for the Ritual Stone is pretty low and the % of drop rate can be increase for enchanting your Settler. So we'll see a controlled inflow of $shard into the open market.
Death. Deeper dungeons have a death rate less than 1%.
Going into the deeper dungeons rewards the player with higher value spoils and more importantly Mythics. This creates the incentive. You can get to the deeper dungeons by going through all the lower ones first to build up Shard Power. Or you can enchant your Settler with $SHARD to go pass the Shard Gates. The balance here comes from a higher death rate for those that are enchanted as they will most likely not have the necessary ATK/DEF and will have a more high chance of death.
So we expect some of the Settlers to take the risk, enchant themselves and head over to the deeper dungeons. This will make some $Shard from the open market to flow in and get burned inside of the game.
We will be carefully tracking the dynamics of players experience to see if we need to rebalance certain dungeons and/or effects.