Very length speculation post ahead!
The most interesting thing about the city courses from Tour, when it comes to discussing how they'd be adapted for 8 Deluxe, is that in their original game they each have multiple numbered varaints; like Super Mario Kart's courses. Unlike that game though, all of the variants are in actuality alternate routes on a single map; with the other routes blocked off depending on the number. It seems 8 Deluxe is taking an intriguing approach to combining these routes into one complete track.
Using Tokyo Blur as an example, because it has the most to go off for the purposes of my speculation. Right here in this press image (and as seen during the direct's gameplay) both the Tokyo Blur 2 (left) and Tokyo Blur 3 (right) paths are available at the same time.
In this view of the course we once again see routes 2 and 3 opened, with item boxes and coins placed on both (clearly indicating that they're both accessible). We can also barely see, on the far left of the screen, a segment of the track from Tokyo Blur 1.
This screenshot from the key art for the pass adds a confusing wrinkle to all of this though. Here we clearly see the Tokyo Blur 1 route open
but you may also notice the arrow sign pointing towards towards that path. In Tour proper, these are typically placed to block the other routes off from access; there's even a set of them right there in Tokyo Blur 1 in Tour!
Unfortunately we can only see the one arrow sign, since the space the rest would occupy is covered by the Mario render. What would it mean if the path was blocked off in that screenshot though? Well, i've got one potential idea: perhaps each lap will take you down a different route on the course.
- Lap 1: Tokyo Blur 1
- Lap 2: Tokyo Blur 2 / 3
- Lap 3: Tokyo Blur 4
I haven't actually mentioned that last one yet; since Tokyo 4 combines segments of the prior three variants into one. I think it'd only be represented here if my above theory is correct; definitely isn't the one and only route (another potential conclusion you could come to based on what i've presented so far) because in that case
Mario would be driving the wrong way in this clip!
I don't know if i'm entirely sold on it myself, though, because there's a lot of factors to consider in this. I can't recall any tracks that change this dynamically between laps in prior Mario Kart games; and there's a lot of problems that could arise from a structure like this, like how racers behind in a previous lap could interact with one in a later lap with access to another route. So for now I want to assume that the course will just be totally open with multiple routes available on each lap, and that there's really only a single arrow sign there; but there's that other posibility I can't entiely discredit either. Will be interested to see which one turns out true, because i'm sure it'd apply to all the other Tour city tracks as well!