there was some discussion about the service life of Mercedes airbags.
Now I found one relevant document,
Service Information on airbag units
Airbags, that were installed in Mercedes-Benz passenger vehicles up
to January 1992 have a service life of 15 years. After this service life
has elapsed, the airbags must be replaced at the customer's cost.
That means: Airbags installed later than January 1992 have definitely no expiration.
My comment on the date: Maybe there is a newer document available. The document says at the bottom: Copyright DaimlerChrysler 19.11.2005. But this date only says, at what date the document was printed out of the WIS, not when the document was generated. So it seems, the document is from 2005 or older. Whether other documents exists which also extend the life of older airbags is not known to me.