This is a short summary of the future plans for Factorio.
Factorio 1.1 (stable since January 26)
- The 1.1 release is the final release of the vanilla game.
- It will be maintained, so bugfixes, simple modding interface additions, or minor tweaks can happen, but that's about it. 
Factorio Expansion Pack
- The future plan is to release "one big expansion pack", see Friday Facts #365 - Future plans