When can we expect effects to "play" in a true blind state?

Why do effects applied to channels always have to be live. I would like to apply an effect to channels see on my magicsheet how it reacts. Then when I bring it up in live on a sub or cue it plays on set. When can we expect blind to be blind? Next update? I've asked this before but feel only us movie and TV folks need this as we done have rehearsal or prelight days.