As far as those features are concerned, Spinks told Rock Paper Shotgun that while Terraria 2 is "a ways out," it will "have a lot in common with the original. It's gonna be quite different as well. I really want to expand on the whole Terraria universe."
Spinks said that he is "locked" in to some of Terraria's established mechanics, such as "the way loot works" and "the way character progression works." With Terraria 2, Spinks said he wants "to have infinite worlds so you're not just stuck to one world. You can travel anywhere. I want more biome diversity in that, too."
As for Terraria, he added that the recently-launched version 1.2 will probably be "the last seven-month update" for the original game, but that he plans to finish the "endgame progression" for the update "within the next month or two," as the update didn't include a final boss. He noted that while there may be other updates three or four months down the road, he has "looked into maybe hiring another small team to continue updates while I move onto Terraria 2."