I think you hit the nail on the head. This is the biggest thing I think people do not realize. The limb independence used in the last 5 albums is something MP is not going to be able to do. This is something that requires a lot of practice and since MP - by his own admission - does not practice this isn't just a matter of shedding it for 5 weeks. MM has been practicing and teaching this stuff for decades. Pull up almost any song on View and you're going to have select places where MM is using these skills. MP has not be show casing anything like this so again, it's not like he's just going to whip it out after never practicing it for 30 years. This is a very different thing from stitching together complex time signature changes like Dance of Eternity where you need to be able to play the time sigs but the actual parts themselves are fairly basic.
MP is going to bring the songs into his own style and make it work for him but there is no chance this is going to be a replication of what MM played. Some songs are going to transition really well like Paralyzed and others just aren't (Alien, Awaken the Master, View, Pale Blue Dot). Doesn't mean they won't sound great but I have a hard time imaging a faithful rendition of certain sections. There are a lot of good MM era covers where guys are just playing something different at certain time stamps and it still works. As for the other stuff like the one handed single strokes and crazy fast fills....it's just going to be MP's own flair. As it should be.
99% of the audience is not going to notice so arguably none of this matters but this is a topic that is getting a lot of speculation on social media = is MP going to be able to play MM's parts? Even if he somehow you could learn all this stuff by drilling it for 3 months I am not sure that would be the best use of his time right now. MM has his style and MP has his. I personally have no itch to hear MP play View. I'd rather hear him do the stuff HE can do.
It is stunning to me - not just about Mike, but in general - how falsehoods and misunderstandings just KEEP getting perpetuated.
Mike P. said he doesn't practice IN THE TRADITIONAL SENSE, doing skills and drills. He noted in that and in other interviews that he actually plays a LOT, and does a lot to learn new material and make sure he can do the gigs he's signed up for. In my book that is, loosely, "practice". I think we're grossly underestimating his abilities here; there is absolutely no doubt that he will bring the songs into his own style and make it work for him, and I certainly do not expect what we hear is going to be a replication of what MM played, but I think the knee-jerk negative assumption that it's simply because he CAN'T is unfounded and unproven.
I was looking for a place to write this anyway, but since you mention the social media response, I think this is as good a place as any: I recently expanded my presence (unintentionally) on Facebook, and it is STUNNING to me how much negativity there is about and around Mike Portnoy. I don't know if it's just normal social media ignorance and rudeness (which by "normal", I mean seems to be the normal course of business on social media; what a cesspool) or if there is something more, but most of it doesn't seem all that constructive, and rather comes off as gratuitous and/or petty. I found a lot of it unfair and unreasonable.