(EDIT: I hope this didnt come across as rude, it was a great topic and I was just excited to discuss the history F2P and our design!)
The design as a F2P game was never started.
The session based nature is something I want to explore, as a game developer, rather than just doing what everyone else is. I wanted to explore reasons for players to build and ways to recreate experiences again and again. We simply can't support high fidelity game spaces over lengthy periods of time - as performance would tank. This is why games like Ark and RUST have to do regular wipes.
Time will tell if this is a good idea, but F2P was scrapped because of many reasons one of which it was maybe going to impact design. In fact, the designers and the whole team have been consistently forbidden to even discuss monetization in any meetings at all, for any consideration with the game development, whatsoever.