Main computer error on 2001 Grand Cherokee Ltd


I have a 1 owner 2001 Grand Cherokee Ltd. w/ 100,170 miles that I have done all recommended maintenence on up to now. The check engine light came on at approx. 99k and 2 shops ( 1 dealer & 1 private Chrysler cert.) have said that the error for the main computer is showing. The cost is around $850 to repair and the part is on national back order. They tell me my car could “quit at anytime” but it is running completely normal and I am just waiting for the 2008 (now January 08) Nissan Muranos to come out and I plan to trade it in. Should I take the risk or will the Nissan dealer give me the hit on the trade in anyway?