Probably not in the near future. It's a free game and putting games on Steam costs a fee.
Some still do it, like Enclosure 3-D on Steam (steampowered.com)
Feel free to ask a little money for it, i think your other games have been received well enough? You can even put it on for free, but have a DLC as a donation for a cup of coffee (some do that) or some extra stuff for the game.