A:Answer In terms of technology it is already a gen behind the latest technology. With that being said, the current gen technology that is out there hardly any devices themselves are using it.
How often you use it or how much data you stream really shouldn't effect the life of the unit. The question you need to ask yourself, is how important it is to you to always have the latest generation of equipment for top speeds.
I picked this up and at Christmas to replace my eero's I had from a couple of years ago, which were 5G. I replaced the Eero's because, I got tired of not having a true router I could control.
Personally, I think you can get a min of 3 years to 5 years with these in place. I'm an IT director and we generally upgrade our wifi infrastructure every 5 years at our offices.