Or perhaps trading up. I have just purchased a brand new WH Grand Cherokee CRD Ltd and love it........so much so, last week I bought the Ltd Cherokee CRD (slightly smaller) for my wife. Down here in the Peninsula, they just opened another new Jeeep dealership and I actually spoke with the owner from whom I have purchased Nissan's and Merc's before......
He said that Jeep spare parts, a majority of the parts are sourced by both Chrysler/Daimler and Mercedes and supply usually exceed 12-15 years......my uncle had a Jeep Grand Cherokee back in mid 80's and when Jeep left Oz shores for over 10 years, he could still source parts readily......I wouldnt worry too much......maybe upgrade to a new or demo new WH