Yep, what people don't realize is that Wrangler sales have been decreasing since 2015. I personally believe that the reasons for that are:
1) Market saturation. They've finally gotten to the point where they are making so many Wranglers that you actually see them sitting on dealer lots for a long while.
2) Price. JK pricing increased a LOT from 2012 through 2017 for what was essentially the exact same vehicle.
And if you look at JL...both of those points are made worse. They plan to build even more JLs, and as we all know the prices have gotten even more ridiculous.
I personally think the 2018 JL Wrangler will sell pretty well because it's an all new model (just like what happened with JK in 2007 and the 119,000 sales they had that year) but starting in 2019 we'll see Wrangler sales continue to decrease. This will lead to a lot of Wranglers sitting on lots, and will likely end up generating huge rebates on JL models in coming years which is something else that Wrangler traditionally never saw.
Bottom line: They've taken a great thing and they've milked it too much. They've gotten greedy and it is coming back to bite them now.
Did you consider that sales have been decreasing because the model was old, outdated compared to other 4 door options and since not much had changed owners felt little need to purchase another to upgrade....quite common at the end of a models life cycle...Remember, the hardcore guys might not care about that as much, but the typical 4 door SUV buyer certainly does and the really is the bulk of the Wranglers customer...Consider the typical Jeep buyers income demo, its high, the JL is transitioning to something more desirable for their demo while at the same time becoming more capable off-road in a nod to their roots.