The iPad may already be hitting its midlife crisis. According to financial insiders at JP Morgan Chase, component suppliers and manufacturing partners are being told to scale back their orders for the fourth quarter of this year. If true, that would be the first time that iPad production levels have gone backward.

The cutback is hefty, too: down 25%, from a planned 17 million iPads to just 13 million units. This amid widespread accolades for the latest iGizmo and a lack of any serious competitors. If the iPad was losing ground to, say, HP, IBM, or Amazon tablets that might make sense, but the iPad effectively has no competitors, so a cutback in supply-chain orders signals an expected drop in total sales.

What’s up? Has the iPad already peaked after only a few years? Now that the early adopters have snapped up theirs, it’s possible that demand from “normal” people just isn’t materializing the way Apple expected. Another possibility is that Apple is readying a new iPad 3 version and doesn’t want to be stuck with unsold iPad 2 models after Christmas.

Tablet computers are a tricky thing. They’ve been around for a long time (remember the Convergent WorkSlate?) but have never been especially popular. Even now, tablets like the iPad seem more like fun consumer devices than serious work computers. And maybe that’s okay. There’s no rule that says tablets have to replace PCs. Maybe they’re an adjunct to traditional computers and not a replacement. Either way, Apple seems to think that this particular version may have already past its prime.

Update: not surprisingly, other Wall Street analysts don’t agree. They’re claiming that either Apple has shifted its production forward from 4Q into 3Q in anticipation of holiday sales, or that there’s no downturn at all. Naturally, Apple itself isn’t saying.