Xylakant parent
At the moment, this is a theoretical attack using a known to be broken card. But it’s unlikely that this is the only card that is broken. And attacks only get better, never worse, until the theoretical attack graduates to a practical attack. Spectre and Meltdown were long considered theoretical attacks with no practical implications - until they no longer were.
As I understand it, serious smart cards have been explicitly designed and audited to resist power monitoring attacks. There are fancy consultants who specialize in this sort of thing, and I think the major players use their services.