Hardware has the difference that it eventually stops working and/or becomes obsolete, forcing people to migrate to newer models every so often. Code is immortal.
Nevertheless, in Ethernet's case, while it changed backwards incompatibly at the beginning, since then, consumer Ethernet has been backwards compatible all the way from 1990's 10BASE-T (10Mbit) to the still-rare 10GBASE-T (10Gbit). In data centers you have faster variants that require different cables, for routers... but even there I believe the connections to individual servers typically use the old twisted pair.
Nevertheless, in Ethernet's case, while it changed backwards incompatibly at the beginning, since then, consumer Ethernet has been backwards compatible all the way from 1990's 10BASE-T (10Mbit) to the still-rare 10GBASE-T (10Gbit). In data centers you have faster variants that require different cables, for routers... but even there I believe the connections to individual servers typically use the old twisted pair.