I certainly don’t think you should get a new computer unless there is a good reason.
You can certainly expect to use any current computer for at least three to four years without expecting any hardware failures, and with expectations that it will be powerful enough for any software you might want to run in that time period. Business software usually has feature upgrades every one to three years. Most computers built in the last six years should be able to take advantage of any of the software upgrade features.
So what is the reason you're considering upgrading? Do you want a faster, shinier computer, or do you just want the latest and greatest like Ken does?
Changing from a PC to a Mac or visa versa is a big step. I personally think you should buy a computer based upon the best software for your needs.
Years ago the Mac was thought to be better for art, drawing and music applications.
The PC was generally thought to be better for business needs. Today for the most part there are no significant advantages for applications running on a PC or Mac. There however are exceptions.
Again, find the best software for your needs and get the best computer to run your software.