Here's what will happen. Mordekaiser rework will fail. No question. And here's why:
Firstly, Mordekaiser is immobile, CC-less, and deals most of his damage over time in melee range. And they send him in a lane dominated by range, mobility and self peel. Good luck ever landing those 3 hits on Vayne, Lucian, Jinx, Ezreal, etc.
Second, ADCs are gruesomely overpowered. Let's take a look on which kind of champion has went into what lane, over the years:
Top - Tanks, fighters, mages, assassins and ADCs
Mid - Fighters, mages, assassins... and ADCs
Jungle - Tanks, fighters, assassins, sometimes mages
Bot - Support and ADC
ADC is the most important champion on the team - there is a reason there is always an ADC on the team. There is always an ADC in the botlane, and possibly another one in mid or top lane. And to compete with these overpowered champions he is meant to replace on a team, Mordekaiser needs to be overpowered himself, even more so to compensate for glaring weaknesses in said role like lack of range or mobility.
My prediction is as follows: when released Mordekaiser will have an absolutely abysmal win rate, in range of 30-40%, for no other reason that he is forced into a gimmick doomed to fail. Since they can't ignore champion being that bad, they'll start slowly buffing him - until people start bringing him to solo lanes once again once his power level allows that. And then, since CertainlyT (who's responsible for some of the League's most cancerous solo laners and THE most cancerous botlane
) "can't see a way to make him healthy in a solo lane", he's going to get smacked with a nerf hammer until he is never seen in a game again - for no other reason than daring to show his helmeted face in a role outside of the one Riot appointed him, all while they preach how they "encourage diversity" while buffing Lee Sin back into numero uno jungle spot.