I think it can get better, but I have to tell you that my spirited 2 year old still melts down when overtired. It's a very definate sign that we need to get her into bed pronto. However, she doesn't cry herself to sleep anymore--so in that sense, its better. We can calm her down and do the normal bedtime routine and its usually ok, even if its late. At naptime, if we've missed the window, she won't always sleep, but that's a whole other issue.
~Kim