Like anything if you stay on top of your servicing, flush the coolant from time to time, change the trans filter, and all your fluids occasionally, it should run fairly trouble free for a long time. That said after 100k miles you do need to keep in mind that things like the fuel pump, alternator, shocks/struts, ball joints etc, are probably getting a little tired and may fail. They are all minor fixes and provided you can get it in and the parts are available should all be a same day service. Your major components and systems, engine, transmission, transfer case, axles, are all built well and if serviced properly and regularly will rarely fail. This is true of most cars nowadays. Best thing a person can do is change your own oil, it gets you up close and personal with the underside of your car and you can see all your mechanical bits and pieces. You are a lot more likely to notice something like a cv joint boot failure if you're underneath your rig every few months or so. Barring that find a good mechanic who'll give it to you straight. I'm not afraid of mileage as long as I can see a complete, or nearly so, service record and I know someone took good care of it.
