I'm all for the change in format because the best parts of the show are the segments/specials. However, I will be more than a bit miffed if we don't get the quality car reviews we've had to date. Some of the segments about some of the super cars, are just pure car porn, and I love it. Especially as it's unlikely I'll ever own a hypercar Ferrari, McLaren, Bugatti etc.
They will most likely have specials involving super cars on the Grand Tour but as I understood it there won't be any more traditional car reviews and lap times etc, so you'll probably have to go to Top Gear for those. Chris Harris does car reviews better than anyone anyway, although his style isn't the same as the GT trio obviously.
He does reviews for Top Gear's youtube channel and those videos are even better imo even though they lack the amazing editing from the show, but they aren't scripted so he isn't forced to tell a bad joke every 15sec.. That stuff worked perfectly for the old guys imo but Harris can't really pull it off.