[fjtorres]

I wouldn't expect them to last too much longer.
(Maybe a decade.)
eBooks have created a paying market for short fiction the magazines can't match and the declining circulation reduces the incentive for authors to accept those terms just for exposure, so I expect that over time submissions will wither away, even from tradpub authors. (Witness Bujold's recent novella being selfpubbed: none of the magazines could match even her first week of sales alone.)

The economics aren't in their favor on the author side.

On the reader side the incentive for newcomers to buy into the magazines is pretty low--they don't make it easy to buy digital, they haven't even embraced the web like other magazines, there is a growing number of bargain-priced bundles and anthologies, and the competition for "eyeball time" is fierce. And ebook subscription services loom ever more threatening.

In a way it is surprising they've hung on as long as they have. Subscriber loyalty/inertia, I suppose.