Did you not see the R33 getting modded in the release date trailer? It really seems GT7 is going to include both driving and modifying everyday cars, but also futuristic stuff. Hence that statement from Kaz saying that GT7 is a combination of the past, present and future.
I did see the car modification in the trailer, and that looks good.
The futuristic stuff I would prefer to be futuristic like real concept cars that actually have lineage into cars that will potentially get made. For example, the FT-1 that eventually became the new Supra. Great! Some of the VGTs have been like this, cars that could conceivably be made and sold. But a lot of them are just designed as pure race cars with no clear way that they could evolve into something relevant to a consumer.
I would prefer not to have more imaginary racecars and "technology demonstrators" for technology that doesn't exist or isn't physically plausible. These cars either won't exist or will exist only in extremely limited numbers as a marketing tool. They're not intended to ever be driven by a real human, which I feel is an important characteristic for a game that purports to be realistic. I think if you look at the VGTs that were made before and after the Chaparral, you can see when designers realised that Polyphony wasn't going to pull them up on anything that was too out there.
I'm not against concept cars in general. I think the original idea of the Vision Gran Turismo project was a good one. I think it's gotten too far into the realm of what is essentially engineering fantasy cars for my taste, and I'd like to see it rebooted with a more defined set of constraints - at minimum, that there's a base model of the car that would be drivable by a normal human on a public road. If they want to make racing variants of their road going concepts, then sure.
I'm not making the argument that these concepts should be replaced with real cars, if Polyphony wants concept cars then they're goning to get them one way or another. If they wanted more real cars, they'd have done it already. But I think that these concept cars could be better selected to be appropriate for a Gran Turismo game.
To me, Gran Turismo was and is about real cars and realistic cars. Not fantasy cars made purely so that the engineers can display how massive their tools are. I'm sure lots of people love driving the cars, but lots of people love Ridge Racer too. I question whether these fantasy cars are appropriate for Gran Turismo, when Polyphony could be working with the manufacturers on something more applicable to their players.
For example, what if Polyphony asked all the manufacturers to supply a concept for a road legal electric only GT car with an expected price of ~$100K USD or less? One that could be made and produced with technology reasonably expected to be available in 2025. That's a near future concept car with potential real world applications, that doesn't let the manufacturers simply waltz off into fairy land and probably ends up with a class of cars that will all race reasonably well together.
What if every new GT game then came up with a new concept for the manufacturers to work to? It could be a unique feature of each generation of GT games with distinct differences between them, rather than a cheap tool for car manufacturers to use when they need marketing buzz.