It may be the only Gran Turismo of this generation, unless Polyphony really steps up the pace on GT7.
Anyway, back to your first point:
@ about 8 minutes in. Basically he talks about how these days you can't make a game with slow progression that takes hundreds of hours to complete.
Which is obviously bollocks. Let's put aside the fact that GT4/5/6 are significantly more massive games than GT1 or GT3. There's plenty of other modern games with that sort of scope. For starters there's a whole genre built around milking gameplay for hundreds of hours, MMORPGs. WoW and friends are the kings of incremental improvement over hundreds of hours. I've got something like 170 days played on my WoW account in the last ten years.
Then there's games like GTA V, or MGS V, or The Witcher 3, all of which have well over 100 hours of content in them. You can rush the main campaign start to finish in less time than that, but you can do the same in Gran Turismo games. The only way you ever get 100+ hours out of any GT game is going for completion, so it's only fair to treat other games the same way.
Unfortunately, this is one of those moments where he's demonstrably talking out his bottom. He's straight up wrong that you can't make a massive game. However, what he may have meant is that modern players are far less tolerant of the sorts of lazy pacing and game design that was prevalent 20 years ago. Gathering 20 bear asses is no longer considered to be acceptable content. Neither is grinding Like the Wind for six hours so that you can reach the next level.
Contrary to what he says, it's nothing to do with the size of the game and everything to do with how it's laid out. Players these days are far smarter and far more discerning. They won't just play because it's a game. You have to make it worth their time, which means that they need to feel like they're progressing, that they have agency, that their skill matters, that they're achieving or experiencing something.
Unfortunately, game design is one of Polyphony's weakest areas. They make pretty good systems and high quality assets, but they struggle to present them in a manner that is the most engaging that it could be.