It has been this thought process that has probably sold more ARs than anything else - including a high percentage of them to first time buyers who had never even owned a gun of any kind.I too bought them because I expected they would not be available this long.
Basically the whole AR 'craze' can be attributed to one event that took place in 1994.
There seems to be a shift however away from ARs (and variants) - historically low prices, massive numbers of them for sale used and some manufacturers of them having folded are evidence of it.
Ammo prices also drove many away from AR shooting as unlike levers, bolts or single shots 50-100 rounds might be a shooting 'session' but many AR owners feel the need for massive round counts of several hundred - or much more when out shooting.
Another reason is a large percentage of the first time owners were 20 Somethings at the time - are now 40 somethings (or more) and if even still interested in shooting sports have moved on to other gun styles.
As a veteran (twice over) I shot enough M-16s to satisfy my desires and I simply have no interest in owning one - but actually did at one time and wish I still had it as it was a pre ban 1978 Colt SP-1 AR-15 but I sold it before the wave of AR ownership was even a rising curl.
I'll even admit to a potential thought of owning one again, and even kind of started looking for one but it had to be a specific model - a Colt AR 15 A2 HB Sporter. I came close, and actually found one at a GS a couple years ago but after hefting it I simply realized I didn't really care for the configuration and let it go.