Steam would be so great I really hope that we will be able to polish JJ&BUM in a way that would make this game an interesting material for publishers once it's finished.

It's possible, a rule in life is to target hight, believe in it,
dream of it !
If all the levels have that quality it's possible indeed !
Steam have several section like Arcade , Casual etc ...
If the game is polished in presentation , interface, gameplay,
it can be sold in a section of Steam i think, and it can motivate the team also to target Steam.
Even if it didn't go in Steam, you 'll find another publisher i think also !