[ncmncm]

That is just when signed 32 bits rolls over. Unsigned takes us all the way to 2106.

Nervous nellies worried about rollover, and insisting we switch to 64-bit timestamps everywhere, are a nuisance. You can keep one 64-bit epoch, such as boot time or most recent foreign attack on NYC, and as many 32-bit offsets from that as you like, and always be able to get a 64-bit time whenever you need it. Most often you only need a difference, so one epoch is as good as any, and you can work purely in 32 bits.

Pcap format is good until 2106 assuming the 1970 epoch. A bit of one of the now-unused header fields could be repurposed to indicate another.