Um. Neither PoE nor PoE2 were episodic releases...
PoE was base game + one expansion that they decided to split into two parts because they feared players would lose interest if they took too long to add new content to the game. A decision they later admitted was a mistake. I have no idea what you are talking about re. "the episodes not flowing enough" -- The White March content is easily the best part of PoE and by many considered one of the main reasons to play the game at all.
PoE2 was base game + post launch DLC releases. Like Fallout: New Vegas, and like most other games out there. The DLC were also never meant to tie into each other -- they are clearly separate stories, though IMO they do a great job at tying into the overall narrative. And, again, they were the highlight of PoE2. It seems to me that this is where Obsidian's strength lies -- in smaller, more focused stories, rather than big sprawling CRPG's. The success of The Outer Worlds also seems proof of this.
Turn-based mode was never planned or promised. It was a feature two developers experimented with after all the planned development (DLC, patches, etc.) had wrapped up and, knowing how popular TB is with a certain subset of their fans, they released it as a BETA feature at first, and then eventually as an official feature. It was something for the fans.
All that said... I think the commercial failure of PoE2 had more to do with PoE than with PoE2 itself. PoE rode a wave of Kickstarter popularity and publicity during its campaign, development, and even post-launch, that had very much died off by the time the second game was announced -- and had all but disappeared when it was released -- and I think the hype around old school games, crowdfunding, etc. won them a LOT of sales from people who might not actually have been the core audience for this type of game.
I also think that some people, maybe more than we think, didn't get what they wanted out of PoE. Meaning that, although it looked like the Infinity Engine games, it didn't play very much like them, and the general tone and atmosphere of the story and world didn't feel very much like the Forgotten Realms at all. It was more serious, its themes were heavier, it was very exposition heavy, with almost none of the whimsy a lot people familiar with BG and BG2 might have expected. It was great in its own right, but it might not have been what people expected or even wanted, thus considerably lessening a lot of spontaneous buyers' interest in a sequel.
And yes, I also very much doubt we'll see another isometric PoE game. It's well known that several people at Obisidian are interested in doing a Skyrim-like PoE game, so I would think that's where they will take the series next. Which is a damn shame because the PoE2 rule set / combat and gameplay mechanics are amazing -- IMO the best implementation of real-time with pause to date.
Post edited January 08, 2020 by Lorfean