John D Cook has two posts about The Lindy Effect that are worth reading. (In Cook's words "The longer a technology has been around, the longer it’s likely to stay around.")
(Okay, so neither of us wore Chucks like this, but we do both love Lichtenstein.)
I had no idea this property had an actual name though. The math is convincing. I think the only big assumption is that lifespans are power-law distributed, which seems reasonable and appropriate in many domains.