We had 10:30 reservations at TH last month. They were slow to seat (I've read this is typical there by late breakfast, it seems reasonable to plan on a 10-20 minute wait after you check in) so we didn't get inside until about 10:50. Breakfast was still out but we were told we should hurry if we wanted it, because lunch was coming quickly.
They gradually consolidated the breakfast offerings and put lunch out in its place, so when we went for seconds there were still some breakfast choices available but mostly lunch. If you want a full selection of breakfast choices I would recommend checking in early enough to be seated before 11 (so 10:30-10:40, later than that might be risky?), and you should also have plenty of time to enjoy lunch.
For our group the kids loved the breakfast choices and the adults were really pleased with the variety of lunch options. I was amazed at how many great salads and vegetable dishes were available.
As far as this being new, maybe it varies by restaurant? We did a late breakfast seating at Hollywood and Vine three years ago and were able to have a bit of each meal then, too. They were trying harder to turn tables there so we didn't linger over the lunch options, but they were definitely available. I know a few restaurants do actually "close" between breakfast and lunch, so at those I wouldn't expect to be able to get both.