I still don't know about this mechanic. I live the idea, but I'm having trouble with actual designs for it. See Hindering Vow's comments for diffuse, a possible alternate take on Predict for which I haven't yet designed any cards.

Doesn't predict behave very similarly to forecast?

It's instant speed and not restricted to your upkeep, which is much nicer. You can even wait until your opponent finished their turn and use it then. You can't put it on instants, though, since responding to activating the predict ability by casting the spell is probably bad.

What if Predict was a special action, like Morph? Then you couldn't respond to it, but you could respond to the trigger.