In terms of ages and joing airlines, it isnt really a problem unless you are well over the age of 40, and even then if you have a type rating, fATPL and a good personality an airline cannot turn a blind eye to you as you meet the spec they want, and dismissing you because of age isn't professional, nor is it legal etc etc. Yes a 24 year old looks more attractive in terms of long term contracts and the ability to become a very good pilot given a career of flying within the company, but 'at the end of the day' a pilot is a pilot, as long as you can do the job well and you get on with people you can still fly the big jets and earn money for it.
As for the argument about the economy there isnt a magic ball we can use and there are no magic words anyone can say that will determine whether or not you will go ahead with training. HOWEVER, being in the position myself about to start integrated training and having made one huge decision to live in NZ for a while, I have an optimistic view. Firstly the aviation industry is massivley cyclic, meaning for example, the industry slows right down one minute and booms the next. Take a look at 9/11, a year later after airlines went bust things picked up again. Secondly if you train now chances are you will come out in an upturn- look at all those who thought it was clever to train when things were booming and are graduating now; you get the point. In my opinion, and in the opinion of just about every aviation professional I have had the pleasure to speak to seems to think now is the best time, but thats one to be argued by someone more pessemistic.
For me (oops I've focussed things back on me again), I will graduate with my ATPLf and AQC complete with the possibility of the type rating completed as well in around 2010. This magic date seems to be the general predicted date that things will perk up, and to put the cherry on the top, I will aim to graduate a few months before the summer recruitment drives increasing chances. When you put things in prospective it doesnt seem too bad does it? Yes you have to also think what if the economy is still in the crapper, but if you think like that- especially the older ones in here you will never l ive the dream or achieve anything you desire. In simple if you are stuck in 2 minds about training now, just ask youself, do you have a backup plan? Have you got a way of paying any debt if you cannot get a job- presuming you have taken out a loan of course in the first place, if not, have you got a backup plan or a source of finance to help keep yourself current if you cannot get in with an airline?
Anyway, for the older ones asking the question does age really matter or is it too late, I guess I cant give you a definate answer because I dont recruit pilots, but what I do know is if you want something bad enough you will achieve it, and if you show you have passion, personality and the ability, you will succeed! I say go for it and I wish you the best of luck if you do, the only thing to bear in mind is that the older you get, the more likely you are to lose a class 1. Thats the only problem with flying, everything you put into it, all that hard work and hours of training can be wasted should you lose your medical.