When we heard that longstanding free-to-play gurus GamersFirst (fun fact: they actually own the trademark on the phrase "free2play") were picking up Fallen Earth from original devs at Icarus Studios, we knew that the post-apocalyptic shooter would be going free-to-play not long after. But GamersFirst was playing shy, and only just today announced their official plans to fold the game into the fastest-growing MMO business model on the planet.
Massively revealed the official announcement today, along with some rudimentary details about how the free-to-play system will work. In short, there will be four levels of payment that you can adopt: nothing (the whole game will still be open to you), less than the current sub (all the same content as current subscribers, plus an XP gain), the current sub (same as previous, but with extra rewards and cash shop currency to spend), and higher than the current sub (which has everything already mentioned, plus it gives the bonuses to anyone you group with--and it can stack with other top-level subscribers for ultimate domination).
The cash shop will sell cosmetic items, convenience items that reduce crafting times, and other unspecified goodies. GamersFirst is selling balanced guns in APB: Reloaded, so I would expect them to do the same in Fallen Earth, although that hasn't been confirmed yet. The shift to free-to-play is expected to happen within the next few months.