*I do think think it's a little early to conclude that there won't be offline race series.
A little early? How many times do PD have to tell us what Campaign Mode is before people give up hope of something more? It hasn't changed since the announcement, only the number of events.
Quotes from the recent videos showing it off
"GT has historically always had lengthy single player, we call this one campaign mode. In past games we'd call it career mode or simulation mode"
"The whole purpose of this mode is to educate you through the game"
"There's like 150 drills overall in this mode"
"They're nice and short like mini-games."
Driving School
"You learn the fundamentals of driving a car with basic tests"
"You learn how to drive a car"
Mission Challenge
"You continue learning how to drive with a variety of challenges"
"Puts you into situations that might happen in a race"
"The game gives you a mission to go after"
Circuit Experience
"Circuit experience is basically learning techniques to conquer each track"
"They break up the track into two sectors, so you can learn one chunk at a time"
"Eventually make you do a full lap attack"
Racing Etiquette
They didn't show this in any video and I think from the description previously it's obvious why, it probably doesn't even feature driving, only videos, or if it does, it's again very basic to teach simple etiquette.
There are not going to be race championships and cups in Campaign Mode. It is not about winning races and championships, it's about educating and learing. They've been very clear about that from day 1. There will be arcade mode, but that will still miss the key part people enjoyed, the progression. They'll just be one off events/races.