I've never heard the expression, 'airline pipeline' but I can imagine what it means. I guess it means a predictable flow from entry level jobs to the carrier you want, major airline for example. If there was one piece of advice that every aspiring pilot should heed it is, never burn a bridge. This is a small world and you will run into the same people again and again. One day you'll find some guy you knew, "back in the day" is a chief pilot.
Learn to fly well
Be cool
Make and keep friends
Keep in the game and you can make it to your goal.