This post says quite clearly they are planning to bring them back. It also says there should be completely passive trinkets, which we also don't have yet.
Personally I would love if there is 1 of each out of RPPM, ICD, on-use and passive. The fifth could be the cleave trinket, because it's situational. It's probably too much to ask for 4 closely balanced trinkets though, considering they have to be balanced for many specs at the same time.