If they don't have something new to add to existing races/species, I don't see much point in a reprint, and anything wholly new would presumably have been seen in a playtest.
The Feral Tiefling and other variant options from SCAG are still in print, and while the archdevil-specific tieflings from MToF are interesting, the version they are playtesting for the '24 PHB seems to be moving away from the "infernal/diabolic-only" tieflings we've had since 4e and back toward a broader "pick your heritage" style. If any kind of tiefling gets an update in Planescape, it will be an early version of the '24 tiefling.
Similarly with aasimar - the only reason to give them a reprint is if they were to repurpose the Upper Planar "pick your heritage" options from the initial pass of the '24 ardling. Likewise with genasi, save that there really isn't anything they could add - unless they want to bring back paragenasi...
Again, I could see bariaur sneaking in as a relatively minor variation of centaur, and while I'm not expecting it, you could be right about a version of the second pass ardling making it in, but beyond that, I'm not expecting much, particularly since, on some level, Planescape is the kind of setting where options from basically every existing sourcebook could conceivably be show up - everything they've put out in 5e is a viable Planescape racial option, unless your DM wants to keep options from certain settings (Eberron, for example) locked away from the Great Wheel.
More to the point, though, I think the PC options portion of the book will also be the area where they cover the Factions, and if anything, that is probably MORE vital to Planescape than additional racial options.