Training failure is definitely a risk. Thing is majors hire military guys who don't know how to play the game as well as a prior 121 guy who is likely to have friends that can give all sorts of helpful welcome aboard tips.

The furlough risk is minimal now. Short of some sort of economic catastrophe, retirements alone would cover furloughs over the next 5 years - 10 years by which I figure a major would recover. Sitting reserve in the worse base is possible, but you're on the seniority list. It'd be worse if your regional got Colgan'ed (or Compass'ed or GoJet'ed shortly).

If you're an airline pilot, that puts you in the top 2-3% of driven people. There are always jobs out there for unskilled people with drive and once you're on a major seniority list, you don't leave it. The company will even retrain you to get back flying once it's recall time even if you haven't touched an airplane since you got furloughed. That's not the same if your regional goes under during the downturn.