There was doubt?
When they announced that they would make a "movie" to fit between seasons, this told me that they would wrap up with season 4.
How did I know? I counted.
If you want to syndicate, you need traditionally need three full seasons, or 24x3 episodes. That adds up to 72 episodes.
Add up the BSG episodes, and you get:
13 season 1
20 season 2
20 season 3
22 season 4
My math may be a little wrong. However, the magic number of 72 is VERY close. Add in the special, and you get 70.
My math may be a little off, but those numbers were too close for coincidence. They made a commitment to those extra episodes as a financial decision so that they can syndicate the series.