My guess at this point is that either the villain is being built up from one of the already existing characters or is just someone in disguise playing good guy for now, eitherway, I do agree that we need to see the MV reveal soon if anything, it doesnt have to just open up a fight with the MC straight up out of the blue either (because that would feel a bit rushed), I like if the MV situation here was done like Kira, but consideering the changes in format of this series to "puzzle" instead of the usual "villain of the week", Araki did in a lot of previous parts, this can go anywhere and I could see him extend Jojolion´s over SBR, chap length, over some excuse related to Araki writing this type of format, if this had followed previous formats it would have most likely have around a similar chap length that SBR, but now it´s everyone´s guess until it´s written to the end.
That said, I´ve also been thinking, of other time related powers Araki could come up with for future MV(s) and the only good thing that comes to my mind right now is slowing time and I already know that for Araki to introduce such stand power, he would have to allow in a lot of diversity, in usage, because it would basically be a nerf out of time stopping abilities like the World and Star Platinum, it would feel cheaper than that time stop, if the user could just slow down time in a specific set in amount without no control whatsoever, so I could see Araki creating a stand with some electronic features, where there would be a option for the user to slow down the time flow, by lets say, 0,25x 0,5x, or anything lower than 0,5x and depending on how much magnitude the slowing of the time has, the duration of the stand´s power can be either higher or lower, the duration could work by multiplying the 60 secs one minute has per the amount of slowing per sec, that the user can do, so it´s set in stone the duration limits, with 30 secs being the max (at 0,5x per sec) and other more intense slow timing like 0,1x amount to a 6 second duration of the stand´s power, it would compensate for it´s nerfed eff compared to time stopping and compensate with higher duration a thing time stop and even erasing time lack.
And imagine if a future jojo villain in a future jojo anime series with a slowing time stand would be introduced, we could get some effs of the stand being showcased in the opening, like suddently throwing the opening at 0.25x sec speed, or something of those lines it would be a blast!