This is your estimate for ECHR to take action.
I wouldn't know how to estimate an ECHR timeframe. I think they have a prioritization system, that may or may not be subject to revision as events develop. And now that there's been an exoneration on the more serious charges of murder, and no one is sitting in jail, or threatening to go to jail, this case may have fallen quite low in the cue.
On the other hand, I doubt as many cases have this high a level of profile, and ECHR just looks slow footed and ineffective the longer this albatross is tied around their neck waiting for them to act on an obvious & egregious violation.
My own prediction, and I can't wait to be proven wrong, is that Marasca will reach into cassation's bag of tricks to vacate the calunnia conviction, when it issues its motivation report on the march 2015 acquittals. I think there are some squirrely statutes that basically let cassation do whatever it wants or needs to do to make things right.
Perhaps they'll say the new verdict of definitive acquittal is a logical conflict with the conviction for calunnia, and therefore, the official record has to be put in harmony, and the only way to do so is to toss the conviction?
All speculative I know. But that's my prediction, and I'm sticking to it. I say Marasca sorts out the calunnia conviction, and saves ECHR the trouble.