to my knowledge, pentax does not use "35mm equivalent" to name its lenses. Ricoh does that for its GXR modules and i can understand the reason for that: different GXR modules may have different sensor sizes so its easier to convert everything to 35mm equivalent.
also, the actual focal length of a 35mm equivalent 20-80 would be 13-53... and there's already a DA*16-50 :dunno: what's the point?
a 20-80 is actually a good focal length for what many would call a "walkabout" lens - something like the very popular pentax or sigma 17-70. with crop, it works out to 30-120. i can so imagine myself using this lens

but i suspect that it'll be a pretty big lens.