Not sure where they went but they're back. My kid loves hot wheels and just graduated to micro machines (delayed due to choking risk lol). Not sure if they're back with any popularity, my kid is my only datapoint. Hot wheels on the other hand has a pretty entertaining netflix show. Season 1 was a claymation style and had wonderful voice acting. Season 2 is normal animation style you see everywhere now and a bit of a let down to me because S1 was hilarious but the kid didn't mind it.