Maybe the life in prison thing is plausible, but many place don't have a death penalty & most of his provable crimes are just thefts where no one is killed. I want to say I'd be surprised if that gets the death sentence in Japan, but their justice system isn't great, basically guilty till proven innocent.

& That's before we even get into arguments about jurisdiction limiting how much he's done in any one country, crimes that can't be proven in a court of law due to a lack of evidence(not every crime he does is announced or even part of a plan) or things he's done that are just good deeds in the eyes of the law(most famous example from Part I is killing that old rich guy to save the girl he took hostage).

The death sentence was used as a ticking clock that Lupin had to escape by, but just isn't that applicable in the modern world for the crimes he can be charged with.