I'm not sure why everyone is so dead set on getting a marchisio replacement. If Lemina shows his quality in the last 5 matches of this year and the Coppa, then he should be given every opportunity to be the starter next season until Marchisio comes back.
Yes, he is a different type of DM, more athletic and aggressive, while being less elegant. If it were up to me, I would rather have a 22 year old Lemina nearing his potential, than a significantly older player coming in to be a Marchisio clone at 70% of what Marchisio is.