When the 60 day limit has been reached for a question on a main site, the option for the “off topic” close reason is changed from
off-topic because… (too old to migrate)
See also this answer.
On a meta site, however, the option stays
without the additional explanation. But still, in the next step, the option “This question belongs on another site in the Stack Exchange network” disappears.
See also this related question.