@gaoron: "Boruto kept up with Momoshiki in H2H too for a while"
I disagree. Boruto used a surprise attack that hit momoshiki but it did nothing. Then he used clones and they were one shotted effortlessly and Boruto reacted to one attack of Momoshiki which was by using the Jougan. Other than that, Boruto didn't physically keep up with Momoshiki at all.
"In Boruto, some fodder was escaping in a train, Naruto run to get him but that fodder still was able to tell he's being chased by him. Would post a video but I'm on phone."
Nope, clearly inaccurate. He didn't even see naruto approaching. Naruto passes from his side to the front of the train, that's when he realises that something just passed from his side. And we don't even know if Naruto went at full speed. Also, it is important to realise that the train was extremely near the border of the land of fire, and the leaf village lies at the centre of the land of fire. Thus, Naruto ran half the distance of a large country.
The PIS was Kawaki reacting to the attack, as for tanking it, it makes sense. His enlarged arm got hit and it got disintegrated while what they mean't by Naruto can be killed with it is, IF his actual body/torso gets hit by it.
Base Naruto could somewhat keep up with momoshiki who wasn't serious (even though he was getting beat) and was tanking hits from him continuously. That should put base naruto way above any character in MHA in the speed department. Then naruto can simply use rasenshuriken coupled with speed that can blitz, to kill all might.
@ourmanuel: "This implies that he meant they could do it in one shot rather than over time."
Well, I am not sure if they could do it one shot. Though Shikamaru clearly means that they can destroy it but that doesn't mean they will destroy it over a large span of time. It could be anywhere from one shotting to easily able to destroy it in a small time.
"it also implies that each of the 5 great nations would be at least the size of the USA."