Between Covid-19, GT7 coming soon, and PD's official statement that GTS updates were going to become lighter and less frequent (which I believe was before Covid really started taking full effect), I'd be surprised if we got any update for GTS at this point. But I think that makes sense - why keep updating the current game when a vastly superior version is around the corner? Heck, I wonder if something similar happened with the Hyundai and Bugatti VGTs in GT6, where I think I remember there being demos where you could drive them within GT6, but they only officially debuted in GTS. This would also make sense with the Porsche 917-related content that was slated for GTS, and what do we see in GT7's initial trailer? A 917, plus a 911 GT1 Strassenversion. So I wouldn't be surprised in the least if we get the Lamborghini VGT plus the Porsche content (including the Porsche VGT) in GT7 instead, and I wouldn't mind at all, especially since Covid has put a monkey wrench into everything. I'm sure PD was on a short schedule even without Covid being a factor, too.
But overall, I don't think there's much they could (nor should) add to GTS that would get me to play it more these days, especially when they could just have players experience that content (or those features, UI changes, etc.) in GT7, which will likely be an objectively superior game to GTS; I don't foresee there being much reason to stick with GTS after GT7 is released, PS5 ownership aside. It simply would not make sense from a development standpoint to keep adding updates to what will soon be an outclassed game when you'd want as many people as possible to be playing its successor. That said, if GT7 isn't slated to release until say, late 2021 or early 2022, I could see there being at least a few updates remaining for GTS, maybe even including the Porsche content and Lamborghini VGT.