2038. Maybe, everyone on the planet will be using a 64-bit time_t by then. Who knows?
Don't knock it - at my former employers, all the file formats that we receive 'from the business' as opposed to 'from clients' are specified as COBOL file layouts - the back end is still running some flavour of VMS.
Nicely understandable file layouts, as long as one does NOT have to use COBOL to read the feckers.