I do not know where you got your numbers from but according to Jeep Grand Cherokee Sales Figures - GOOD CAR BAD CAR the Wrangler, Grand Cherokee and the wimpy Cherokee are each at around 200K produced per year.
I think the info. you found is correct. Jeep produces a lot of Grand Cherokees.
If you take an approx. 80,000 north American units for MY 2014 and multiple that by a very conservative $28,000 average purchase price (probably much higher) the gross amount is staggering. Granted there are R/D costs, costs to build/market, transport, and dealer costs... for one model of vehicle there is still a lot of profit there too. If you consider that sales have been trending up, I think the 4Runner will stick around. The bigger concern is how long will they keep it BOF and capable.