Yes, it is possible to play Villagers with 6 players, but no, we won't release an official expansion for it.
The game was originally intended to work with 6, and there are enough villager cards to do it. But, we think it takes a little bit too long with this many players, and it takes up a LOT of room on the table. For these reasons, we're comfortable to recommend the game at 5 players, but not at 6.
If you insist on playing with 6, you can print out an extra Founders card from the Print & Play files and you're good to go.