For example, I imagine it would be like silver flipping gold's market cap, (which is practically unthinkable) however, this event would forever alter how gold is perceived, especially by new potential investors.
Platinum has done that in value per kilo though it has many of the same properties as gold, is less reactive, more conductive and used as a catalyst in a lot of places.
I'm not sure if perceptions changed kuch with that as gold didn't seem to do too much better out of it. Eth might be different though but I think there would be a lot more caution by institutional investors due to the increased potential for vulnerabilities (because it has extra functions).