Technology will always advance. If you need/want the computer now, then buy now. If you don't, then wait for the next one when you do. However, you could end up waiting forever because something newer and better will always be around the corner. I don't see the point of carrying this worry. Life can be stressful enough already. Obviously it's a good idea to consider the realities, like, is the Mac due for an upgrade, then perhaps it's better to wait, but asking questions like this when the computer came out a week ago seems frivolous, in my opinion.
I don't get this concept of "the lifespan of a computer" that people have come up. The computer will keep working even when a newer model comes out. Just because a newer model comes out, it does not mean that you computer somehow becomes slower than it was. If your old computer is no longer fast enough to do what you need it do, or the newer computer can speed up your tasks, or give you more enjoyment, then you upgrade. We're not talking about getting married for life here. We're talking about a box with circuits here.
This is especially pertinent when one considers Macs, because it has been proven over and over again that you can quite easily sell every year, or every two years, and buy the newer model without taking a huge financial bath. When you work out the total cost of ownership per day of doing this, it is actually quite a reasonable proposition.
(Having said that some of us are hoarders and find it hard to get rid of our Macs, even when getting another one 😱 )
