There is no update for Chromecast Ultra or Chromecast Audio this year.
This Chromecast guide explains the new features of Chroemcast 2018 (3rd gen of Chromecast), and whether it is worth to update your Chromecast.
What are the new features in Chromecast 2018 (3rd gen of Chromecast)?
Chromecast 2018 is a minor update to Chromecast 2015 (2nd gen Chromecast). So, there are no jaw-dropping new features in Chromecast 2018.
Because Chromecast is so unique that there are no serious direct competitors in the market, it is hard to judge whether Chromecast 2018 is behind or ahead of the industry trends.