I know that Esgaroth and Erebor will be updated (Eventually), and this is not a suggestion for Lake town or The Dwarven Fortress. This is Merely a suggestion for some things to be included when(ever) they are added.
Biomes:
The Long Lake: a normal lake, but random variants of Charred and Rotten wood can be found along the lake's floor.
Erebor: when a certain (or Random) amount of gold, silver, etc, etc is mined, the player will get the Dragons Sickness Effect. can only be removed by leaving the Erebor Biome.
Structures:
Smaug's Corpse: Randomly found somewhere under the lake's surface. Made of Blocks of Bone (see below) and Flesh Blocks (See below). When randomly walking around near the corpse, you can randomly pick up items (Coins, Random Ingots and Nuggets, Mithril being possible, but rare, and Dragon Scales and, Dragon Claws / Teeth. After a random time of picking up some of the Dragon's loot, they will get the Dragon Sickness Effect (See Below)
Sunken House: a wooden structure found at the Long Lake's Floor. made of Charred and Rotten Wood. loot similar to the chests found in the destroyed houses in Eriador.
Blocks:
Flesh Block: made with 9 rotten flesh in a normal crafting table. found in the corpse of Smaug. when stood on, the player will sink into it. can be eaten, and gives the as effects as eating rotten flesh, but 9 times over.
Bone Block: it's basiclly the 1.10 Vanilla Block.
Items:
Dragon Scale: can be used to plate armour and make it stronger, and resistant to crossbow bolts and Arrows. Otherwise decorational.
Dragon Teeth: Can be used to make a Dragon Sword. Otherwise decorational.
Dragon Claws: Can be Used to Make a Dragon Sword. Otherwise decorational.
Effects:
Dragon Sickness: the Player can only get Dragon Sickness from going near the Corpse of Smaug. Gives the Player Nausea, Strength, Speed and a slow, Golden version of the Wither Effect. Also slowly Turns the player vision Golden.
(I have no proof of Dragon Scales, Teeth and Claws being made into Armour and Weapons, but if a Dragon Slayer (or a person manages to find a dragon Corpse) wouldn't they like to show off and make Armour / Weapons from it's Materials?)
Thanks for reading!
Edit: ~Adjusted title to ensure it covers the topic.