Forum activity depends on a lot of factors. New entries into the marketplace tend to get a lot of activity. Rumors of new updates get a lot of attention, as do the updates themselves. If there is a true issue with a device or an update that tends to get a lot of attention, but frequently the issues are on a couple of devices and the vast majority never exhibit the problem.
Many moons ago in a forum far, far away, we did an impromptu study and found that the loudest most aggressive "screamers" (you know the ones, this update screwed everything up, I'll never buy another xx phone again, you hate your customers, this update screwed up the phase of the moon ...) never reposted after their original rant. We did see instances where an update did botch something up and you saw it everywhere on every forum and the carrier/manufacturer quickly replied with a patch. But, most of the time, when someone comes on with the, "OMG, my phone is unusable. This update screwed everything up, how could they release such crap?" You look in other forums and see little if any about the issue, most of the time the issue is a user issue not a device/update issue. That's why they disappear immediately after posting. Sometimes there are issues that crop up that are the result of an update, but a FDR usually fixes them, but on after the ranting begins.
All of that said, a "lul" in activitiy on a forum usually means that things are going well for a particular device. Of course, when the device is truly at the end of life, they die down also.
