Given PD's history, I don't believe that GT7 will receive revolutionary updates, which will suddenly add a relevant number of modern racing cars and super sports cars and several circuits. Its GT7 structure is this, and it will not be now after almost three years that it will be reinvented.
I think that until the end of 2025 we will continue with this pace of updating, that is, one or two circuits perhaps, half a dozen modern and electric cars, another half a dozen classic street cars and two racing cars, probably.
The year 2026 should be sparse with updates for the new game to be released at the end of the year.
You talk about GT8, but I don't believe that this will be the next PD game.
Based on historical references, PD has always worked with an appetizer or preparatory game before launching a numbered game.
I speculate that PD will launch GT Sport 2 or something similar, probably at the end of 2026, taking as a reference the launch window from GT6 to GT Sport, and GT Sport to GT7.
And, in this game, the new GT3, GTE, GT2, LMDh, LMh, TCR racing cars should appear, and also some fictional ones, in short, those cars that we are all wanting for GT7.
After all, that's what PD did within the production window between GT6 and GT Sport, producing several new, modern and original racing cars that we had never seen in the franchise.