I feel like I've seen baits gain and lose effectiveness as they lose and gain popularity, respectively, for quite some time. I've always figured it's sort of the nature of the beast as a fish that's been stabbed in the face by a bait is almost assuredly less likely to bite that bait in the future. As the population of fish that have been caught by that bait increases, there are less fish willing to eat it. Then you've got an entire generation of fish conditioned not to eat a bait, its effectiveness dies off, and guys stop throwing it. Eventually you've got new fish coming around that haven't seen it, and the cycle starts again. Maybe I'm giving the fish too much credit, though I think there have been studies done on bass becoming conditioned to certain profiles (and related results suggesting that they don't become conditioned to certain other profiles).
I've not noticed this happening with crankbaits, though I'm a horrible crankbait fisherman so that probably doesn't help matters much. In fact, if I had to go one way or the other I'd probably say that they have gotten a little
more effective around here, though I think that's driven in large part by more guys being willing to risk losing them to toothies and actually throwing them. MN is decidedly different than much of the bass fishing world, though, and I suspect that crankbait effectiveness will begin to taper off if guys continue throwing them a lot.
The bait that jumps out at me most for exhibiting this is the spinnerbait, except it's one that seems to have gotten "stuck" at not being as effective (relatively speaking, of course...I'm certainly not saying it's not effective anymore, it's just that it's not as effective as it once was and there are often better ways to catch them). I keep expecting it to turn around since many (not all, but many) of the "serious" anglers in my neck of the woods have all but stopped throwing them, but it has not seemed to make a comeback with the bass at this point. I think this is driven at least partially by it being the first thing a non bass angler will pick up when the walleyes or crappies aren't biting, so the fish are still being conditioned not to eat them. Other baits I've seen it happen with recently are frogs and Whopper Ploppers, both of which were like cheating for a time but which have quickly become far, far less productive (at least for me) than they used to be. I suspect that the chatterbait is quickly headed in that direction as I can definitely detect a drop off just from two years ago to this past season, though time will tell. Not willing to name off the baits that I've seen make a comeback after having tapered off....