After returning from Laugh Tale, Shanks and Buggy are reunited with the rest of Roger Pirates. Shanks asked something about Roger’s final voyage, but he cried after hearing Roger’s answer.
Maybe Shanks asked Roger afterwards if he could go and conquer “Laugh Tale” later with his own crew, and Roger told him that the next pirate king is fated to be a “D.”. That’s why Shanks is crying, he understands that he will never be able to surpass Roger no matter how strong he gets or how far he is able to go.
That would be the reason why Shanks never went to Laugh Tale afterwards and hasn’t taken the crown of pirate king despite knowing the way, he understands that it’s impossible for him.
All this also gives bigger meaning to what Shanks said to Luffy in very earliest chapters after Luffy told him that he’s gonna be the king of pirates: “Oh, you’re gonna surpass us, then.”
On that moment Shanks realizes that Luffy has what it takes to surpass Roger, to do something Shanks himself could never do. Then he decides to take off the straw hat, put it on Luffy’s head, and bet everything to Luffy and his success, ultimately letting go of his own childhood dream.
The way Shanks is depicted in the latest chapter is almost identical to Luffy crying to Shanks in chapter 1, being an obvious parallel between the two.
In a sense, Roger was to Shanks what Shanks is to Luffy now.