The official Phantasy Star Online 2 website states that "eight years' worth of content is coming to Phantasy Star Online 2 in North America". The website has shared the content roadmap for 2020 and includes a bunch of additions to the game. Story content, mini-games and more, these are the new additions to PSO2.
The website states that a new episode will be added every month. Every episode has a new story, locations, events, player classes and more. There are no details on what exactly these additions entail, the roadmap is more general. Episode 4, 5 and 6 will be out this year with 4 & 5 being released in Q3 and episode 6 on Q4.
PSO2 has revealed the new classes coming to the game. We are getting the "Hero" and "Phantom" but no details on their skillset were revealed. Our guess is that the developer will eventually release trailers or blog posts on what these classes are able to do.
The level cap will be raised to 80, then 90 and end on 95 when Ep 6 is released. The new difficulty mode "Ultra Hard" will be attached to Ep 6 as well. However, Sega (the game's developer) states that this roadmap is subject to change due to the uncertain times. Here is the official link to the blog post in case you want to read more.
PSO2 is available for the Xbox One, PlayStation 4, PC, Android, iOS, PS Vita and Nintendo Switch