Now, obviously, this isn’t confirmed but we should know by now that women in One Piece don’t age well compared to their female comrades. Two good examples are Big Mom and Shinobu. We know through flashbacks that both characters looked very different to what they look now in the current time.
However, Big Mom’s comrades in Kaido and Whitebeard, looked very much the same (muscular wise) in their old age. The same applies to Shinobu’s comrades, the ones that didn’t travel through time that is. The male characters still look quite muscular but despite Shinobu still being a formidable fighter herself, her appearance has changed vastly.
Therefore, we can assume that the same One Piece logic will be applied to the Straw Hat crewmembers in Nico Robin and Nami. This means that they will likely not age well.