It's not silly. This is one of Gran Turismo's shortcomings. Their car list is always lagging behind behind other racing games, to a degree. You like the older stuff, great. But what about those who like the greatest and the latest, and not just because it's the most recent but because they genuinely like the new car? There's gotta be a balance. For example, it's criminal that the most recent Ferrari in GT Sport is 5 years old. If this was a game like GT Legends or Rally Trophy, which aim at classic or vintage cars, it doesn't make sense not to try to be up to date.
We are theorizing here after all. It's in the name of the thread. We try to follow lines of thought into what might be coming. Of course, none of us are sure. I think it makes sense for us to get an update with double-digit cars (maybe even around 15 them), this time around, because, as another member pointed out, Polyphony will be able to say: "In our first year of post-launch support, we have added over 100 new cars into the game, free of charge." Quite the selling point number, indeed.
Polyphony are feeding us a bit too much of the same dish again, for my taste. Let's hope we start seeing some more new additions.