I feel the whole rework should be reverted actually. It's a mess.
The gameplay changes further push him towards a feast/famine style of gameplay [either oneshotting people with third stack 1700 damage Qs, or getting kited to death], which Riot themselves have said in the past is a bad design.
A lot of the changes do not match Morde's theme [he's a healer now?] or have tenuous connections [he summons dragon ghosts now?] which further confuse his already confused identity [the mage bruiser tank is now also an ADC and a healer?].
The addition of two big new features to his kit, the Dragon ghost and duo lane XP, mean that Morde's other unique gimmicks, damage based shield/controlling dead enemies, had to be nerfed in comparison. This means he is now a jumble of overall less impactful abilities, rather than clear-cut, strong abilities which make sense to enemies playing against Morde.
While one of the reasons discussed for changing Morde was his unhealthy laning, this rework doesn't fix that. Giving a botlane duo a free, endlessly useable heal almost as strong as Taric's, a 2 level advantage over their lane opponent, while mildly reducing Morde's range and not really changing his playstyle means he is still a huge lane bully but now he gets built in sustain and bonus XP to go with it.
The new Mordekaiser is heavily rewarded for having a good team and good support [for instance, a Thresh support removes Morde's problems of immobility and lack of CC using his Lantern and Hook and Flay and thus holds down people for Morde to three-shot them], but without a good team and good support, he cannot access his own W ability alone, is slow, and has no way of landing his own Q on anyone with mobility. It's like if Yasuo didn't have a knockup on his Q and couldn't ult alone without a good knockup team. We all know how rare good teams can be in soloqueue. Please don't leave me at the mercy of matchmaking even further.
As a result I predict the new Morde will have a low winrate in soloqueue, but will be permabanned anyway because duo queue players who actually know how to use his duo lane potential will dominate every matchup.
Being a longtime Morde main, I would like to see all changes scrapped until they have time to do a Sion-level rework. If these changes go through they're going to have to gut him after release anyway.
Right now Morde is sitting on a 50% winrate and 2% playrate. He needs no changes unless they're very sure of what they're doing, and it doesn't look like they are right now.