Hello,
my guess is, it will be similar to GPU and CPU price developement. Shiny new, low production, no competition -> expensive. After releasing some better versions (and with mass production), price for the old versions declining. More competition is going to push down prices additionally...
Difficulty will simply adjust to the state of technology. That moment of adjusting, from relative GPU "low" to "ASIC normal", is what drives some people crazy, like in a gold rush.
Another guess: this belongs to mining speculation.
Have a nice day.