Meltdown doesn't exist on them at all.
There was only ever one vulnerable ARM core and nobody has shipped it yet.
El Reg, of all orgs shouldn't be eating Intel's FUD.
The vector that might exist is Spectre.
So given that Spectre requires running your actual code on-target, it seems that network switches are going to be pretty safe.
Unless they expose a (web?) management interface accessible from a "normal" port that already has an exploitable vulnerability. Then they might also be vulnerable to Spectre, but it was already game over - so who cares?