I mean, assuming you like it, a newer car comes with complications the T4R doesn't have, computers and sensors that constantly go bad, this is one of the last cars that is still fairly mechanical. For reference, I had an AMG for 5 years, and it was a lovely car, but at a certain point the stuff that started failing, had nothing to do with the mechanical components, and everything to do with electrical and computer components. I replaced the ECU for 2500 bucks, the chip key system for another 1200, and random sensors for ~1000. In the meantime, the engine and transmission were solid as could be.
I sold it, bought my Carrera and never looked back.
So long as the frame and the body are solid, you just have to keep replacing rubber, suspension, brakes, and eventually overhaul the engine and transmission. I guess maybe do a repaint sometime if you feel like it? All of that together is cheaper than most new cars.
Also, the 4Runner is one of the only trucks that you aren't making a ton of sacrifices for the mechanical simplicity it has. Good A/C, decent interior, decent power (stock or supercharger). Need a backup camera, GPS or bluetooth? There's great aftermarket stuff to take care of you. There isn't much you need to do to keep it current.
If you've put 270k on it in 14 years, even if you rebuilt it tomorrow, it would probably take you that long to put on another 300k and then how old would you be?
So long as nothing catastrophic happens, I plan on having this car and my Carrera until the sun explodes.
The only thing I'd consider getting if my commute stays long, is a battery powered car, but the 4Runner would be my workhorse, and the Carrera would turn into a lightweight track rat.