The goalposts just keep moving.
I think it really depends upon motivation and drive but age does make a big difference. I can't think of anyone I know who 'has always wanted to fly' and got their first commercial flying job past thirty. If however it's a case of a total career change to aviation and your a proven success in another field then its a different story. The big problem within Europe at the moment are the large numbers of experienced pilots on the market with more to follow Easyjet and Rynair are simply snapping these guys up and filling the balance with 250hr cadets. Not good news for many, but its happening.