It looks like the Track Builder packs that were previously exclusive to Toys R Us are making their way back into stores.
I was doing my normal browse down the toy aisle at my local Kroger when I noticed a few of the Toys R Us Track Builder packs on the pegs. They seem to be a bit more expensive than I remember them being at TRU, but they do include a car.
Not sure if any retailer will claim these as "exclusive." The one at my Kroger didn't have any branding to suggest as such, but I wouldn't doubt the Walmarts and Targets of the world getting in one some exclusivity for track pack parts in the future.
Nonetheless, I'm happy to see these packs back in stores at some capacity. It's nice to know that I won't have to buy bigger playsets just to get some curves, loops, or jumps.