Exactly my thought. I'd do whatever needs done to get rid of that dropping cylinders business and just let it run as a V-8.
For driving the Yukon longer-term, Figure between now and 125K Mi or so you're going to probably need:
Shocks and some front-end suspension wear parts, if/when doing tie-rods or control-arm bushings I'd have them take a serious look @ wheel-bearings and or whole hub assembly. New parts are a lot cheaper than labor 2x
Spark-Plugs
Complete fluid flush of every system (trans, transfer case, diffs, coolant, brakes, power-steering)
There isn't much a person can drive that between 80 and 120K Mi isn't going to need plugs (assuming gas), some suspension work, and a full fluid swap. I guess I just consider that as part of maintenance, not "failures".