As mentioned in the video, by the time this was developed anti-tank rifles were pretty obviously obsolete. The US had bought some Boys anti-tank rifles from Canada though. The curious thing from my perspective is that the US didn't develop one in the early to mid 1930s at the latest.Winchester made a (Williams) .50 BMG anti tank rifle but it was never issued. I recall saw seeing something about it on Forgotten Weapons.
Okay, just found the link.
The real successors to the anti-tank rifle were things like the PIAT, bazooka, and the like.