Fix your FX/QX 70 the way you like it and drive the wheels off of it. My '03 is sitting in my next door neighbor's driveway for a third life with 240,000 miles, but going strong.
I'm so happy I just got a low mileage 2013, it should last the rest of my life, if I don't do something stupid.
Saying the QX50 is the replacement is like saying the FX was "just like," a Murano. Only clueless people believe that. Infiniti has some great stuff, but some knuckle head decision makers. But, when you look at the FX/QX70 sales figures vs their other models, it's easy to see why they are going in another direction.
Sigh....