At present the content of a Horadric Cache is not affected by the difficulty level you were awarded it on. Complete the Bounty on Normal or Torment 6, it matters not a jot. This encourages split farming on normal difficulty for groups to speedily collect caches and hopefully desirable loot. Blizzard has recently said that is definitely not the style of play they wanted.
In response to someone asking “why oh why…” Grimiku revealed that the devs are making two changes to Caches and they are:


The second is to increase the chance that you’ll find a Legendary item in Horadric Caches, including Act-specific Legendaries like the Royal Ring of Grandeur, based on the Torment difficulty.
What this means is that Horadric Caches earned in Torment I+ will be able to drop Torment restricted Legendary items, and caches earned in Torment II+ will have a scaling bonus for dropping Legendary items (which includes those items only found in a cache).
And the difficulty of Rifts will also bear more significance soon as changes are planned there. Grimiku explains:
As a reminder, the scaling bonus chance to find Legendaries you get for Torment I-VI slider stacks multiplicatively with the 100% bonus chance to find Legendaries while in Nephalem Rifts.
In short:
- Horadric Caches will be able to drop Torment-only legendaries
- Higher Torment difficulty increases the drop rate of legendaries (including Torment-only and Act-Specific)
- Blood Shard drops from Rift Guardians will increase with each difficulty From Torment 2 upwards
All these changes will come with patch 2.0.5 – for which there is….all together now……no release date.
Interestingly, someone in that thread said they opened 20 Caches and didn’t get a single legendary! From my experiences which I recently detailed in a video and that of others in the Horadric Cache Data thread the 10% theory seems to hold true. Maybe he was just very very unlucky.
These are great changes and I can’t think of a single reason that playing on harder difficulty should not be rewarded accordingly.