Given that Tokyo Expressway got a new layout, that leaves the following original courses to obtain new layouts:
Alsace
Colorado Springs
Sardegna
I'd tentatively include the Northern Isle and Broad Bean, as we did see new layouts with Blue Moon Bay, but I'm not as sure. Whereas those other three courses I listed follow the same "naming" format as the other areas that've obtained new layouts, e.g. Dragon Trail. Meanwhile, Fisherman's Ranch does not have a similarly specific subtitle, so I don't think we'll see a new layout for that one. On top of that, I'd wager that if Colorado Spring or Sardegna get a new layout, it could coincide with more Gr.B cars, especially since some automakers known for real-world Group B cars are conspicuously absent from this group, even if their respective cars appeared in prior GT games, such as with Peugeot and Renault.
(Ideally, I'd like to see additional layouts for the real-world courses, too, even if the variants aren't new to the series, like Nurburgring GP/D, or the 80's version of Fuji, but it'd especially be awesome if we got new-to-GT layouts like the "little Monza," the Le Mans Bugatti Circuit, or maybe the much longer version of Spa. But I digress.)
On a side note, the MiEx should've updated this morning - anything interesting show up? Even some OEM paints?
EDIT: I also heard that the made-for-game race cars, like the Alfa Romeo 4C Gr.3, took a lot more effort to make on part of PD, and that they'd rather focus on integrating real-world race cars between the two of them, so take that for what you will. That said, I think we could potentially see older made-for-game race cars be put into Gr.3/Gr.4/etc. like the RM & Touring Cars from the PS3-era games, or even remade versions of the older LM Race Cars like from the PS2-era games. (Though I'm unsure if race cars based on cars that were concepts at the time but were later mass-produced - such as with the 2001 Nissan GT-R Concept, or the concept versions of the Nissan 350Z & Mazda RX-8 - should be left in the past or not...)