cycloneshooter,
That's a good question.
I saw a short magnum for for this first time this year in an elk camp. I honestly have not seen any other hunter use s short mag. I know nothing about them. I couldn't tell you if they're a fad tat will pass or whether they'll stick around. What I do know is that the .243 Win, .270 Win, 7MM-08 Rem, .30-30 Win, .308 Win, .30-'06, 7MM Rem Mag, .300 Win Mag, and .338 Win Mag and assuredly others that I've missed will be around for a long, long time.
BTW, I still can't figure out why the .280 Rem isn't more popular. In my opinion, it is the best cartridge for all North American big game. Were I a bright dude, I'd own one.
From what I understand, many short magnums are no longer chambered such as the 7MM SAUM & .300 SAUM and Winchester's super short magnum line.
Gr8bawana gave you excellent advice. The 7MM Rem Mag is the most popular magnum cartridge in the world for a reason. If you hand load, you'd find that it will easily surpass factory published ballistics. For instance, I can easily get 3100 FPS with a 160 grain Partition out of my 24" barreled 7MM Rem Mag. I did break 3200 FPS with a 160 grain bullet, but it wasn't as accurate. My 150 grain Nosler load came right out of Nosler's manual. I've choron'd it at better than 3200 FPS. And it will shoot ragged one-hole groups.