I feel like turning up the taps on new legendary items should not be immensely difficult. Sets, perhaps moreso, to be fair, but given the wildly disparate power level of the current status quo, I don't feel like flooding in new items into the item pool is likely to harm much. Also, it's not like they haven't added a bunch of 'transmog-only' gear that they could hijack and use for art assets for legendary items.