You can think long-term while also delivering software for a fly-by-night platform. You just have to understand the difference between an app or business model and various instantiations of that app or business model.

Just because Garmin's software for the Palm OS is obsolete doesn't mean Garmin is obsolete. The iPhone OS was originally developed for the NeXT cube, before many HN readers were born. Microsoft Word was originally written for Xenix systems, then ported to DOS, then the Mac, and finally ported to Windows. The obsolescence of the DEC PDP-7 didn't hurt the Unix platform. The fact that all of Electronic Arts' software is hopelessly obsolete within a handful of years hasn't stopped them from staying in business for decades.

There are apps being prototyped on Facebook and the iPhone today that will have decades of life on one platform or another.