Do I think the 338 Lapua is just a fad? right now not sure but I hope not. as long as firearm companies keep making rifles and brass and components are available then I think it will be a strong ongoing option.
I don't feel the fad thing is related to the public but rather than manufacturers.
I don't think manufacturers are really on the bandwagon with what the public wants.
the are great cartridges out there that if allowed to prosper would do well.
take the 300 RUM and that family of cartridges for example. I think they are really great performers. Remington just did not follow up well enough to really help those survive...I think they are going by the way side. too bad too. I owned a Sendero 300 ultra. great rifle. had a brain fart and sold it. was considering getting another at this moment in my rifle hunt. I have a couple hundred rounds of brass just sitting at home. there are a few new Senderos available. but, no one can find any brass, anywhere. Seems like Remington in their infinite wisdom has decided to only sell loaded ammo. I cannot afford to only purchase loaded ammo. so, I won't purchase the rifle. most people who would consider this type of round are involved in reloading.
look at the 6.5x55 swede. I am not calling this a fad round. but great cartridge. in a modern rifle with better brass and higher power loads would run well with the 6.5 crowd. but for some reason the rifle companies don't make rifles in that round. maybe one here or there but the rifles designed do not exploit the long range accuracy potential of that cartridge. I shot and old military rifle in the swede. what a great shooting, smooth, fun time. would love to own one.
the WSM family of cartridges are great, accurate platforms. but once again the rifles being offered for these don't seem to exploit the potential of the cartridges.
I think what may be the saving grace of the 338 Lapua is the huge interest in long range shooting and hunting. seems like long range is here to stay and manufacturers are getting on the bandwagon selling products to promote this sport. just look at what has come out in the past 15 yrs or so....range finders with incredible capabilities, bullets with high BC, high power scopes with unreal glass, on and on.
as long as long range shooting/hunting is promoted I think many of the new "fad" cartridges will live on. we need them to.