Terraria is set to get a massive free expansion with the huge Journey's End update, sadly it's not going to make it out the door this year.
When they properly announced it earlier in June, they said the aim was for this year but they were still sticking with a "when it's done" approach. In a recent status update, they said that it comes down to a choice between scrapping a "bunch of the cool stuff that we want to see in Journey's End and force this out for 2019 or go ahead and push it into 2020". So, they decided to push it back but they're "fully confident that the final product will be well worth the wait".
Missed their previous trailer on the update? See it below:
Always a shame when such a huge and exciting update to an already fantastic game is delayed, however it's always preferable to have a delay rather than a rush and it be in a poor state at release. Too many developers end up crunching away and burning out too, so taking their time to craft something awesome for their fans is fine.