It feels like GT Sport was a testing ground for a lot of things that will be further refined in the next GT title. I don't just mean the eponymous ranked multiplayer mode, but also the companion app that never seemed to offer much, the social media system that's in-game, the new grouping system, the livery editor, the championships, the daily race rulesets, the lobby options, and stuff like that. It almost reminds me of how some cars in real life will be somewhat transformed into test mules for new models, like we saw for the Ferrari Enzo. It seems like when you look at GT Sport, there's a ton of potential for various expansions, adjustments, and streamlining when it comes to the future of the series.
I'm not sure if we'll necessarily see the changes that GT Sport could benefit from, especially if the next GT is intended for the PS5 launch window, but I'm still interested both the future of GT Sport and how the next title will borrow from GT Sport. There are a lot of details that I could speculate about, from how they plan to tackle certain ideas/problems to if they plan to integrate certain details, but these things are ultimately going to be left to PD's discretion - and yet, I think that's what makes the anticipation so exciting.
We already have at least three updates confirmed for GT Sport, with the redesigned 917 and the VGTs for Porsche and Lamborghini. I also really don't know how much they plan to slow down, even if we're only getting about four cars per month. That's still a decent amount, in my eyes. I also don't really know what's up with the circuit experience for Laguna Seca coming at the same time as the track itself - or if it's indicative of anything at all. Even if there wasn't a track planned for January, I recall Spa-Francorchamps being similar, where the Circuit Experience for that course was still added the month after the track's release, in an update that didn't necessarily include a track itself. Maybe PD just wanted to have the Laguna Seca Circuit Experience available for players who're just getting the game now for the holidays, rather than having them wait until the end of January.