Some software will be broken anyway, and then people will have a choice: to upgrade, or to deal with some broken version somehow. For example: timestamps have four bytes allocated. Which means, that after year 2106, we will be forced into hard-forking anyway.

Another example: year 2038 problem. Many people thought we are resistant, but some versions are not, because of type casting between signed and unsigned, and between 32-bit and 64-bit values: https://bitcointalk.org/index.php?topic=5365359.msg58166985#msg58166985