Since farming during the GE event's i managed to stack up 49 proficiency cache's along with my weekly. I do not want to open them because I'd like to save them for 1.8 with a chance of possibly getting an exotic or maybe even The House or Big AL. But my question is will stuff from 1.8 loot table drop when i open these or will it only be stuff from 1.7?
Judging by all the other patches that have released new content the proficiency caches get treated as legacy items. But whether that is different with 1.8 as there isn't actually a gear score increase happening who knows? I'd be surprised if there is a different loot table used for pre 1.8 proficiency caches.
Best thing to do is to stockpile exotic, weekly or large darkzone leaderboard reward caches in the hope that the new exotics will be included in pre 1.8 cache loot tables. I have 43 caches and counting across my 4 characters that will give me gauranteed exotic drops... so I hope the grind is worth it!