By when should a career academic have obtained a PhD?

I'm 38, and a senior lecturer in New Zealand. My attempts to get my PhD started have been stalled many times over the past years, and I am getting seriously despondent about the whole thing. In the US and Canada, university personnel don't seem to have PhDs as much as they do in the Commonwealth system, I noticed, and everybody still seems to live happily ever after. Would I be safe to postpone this whole hullabaloo until I really feel like doing it, or is it high time I get this over with?