The future perfect continuous negative tense is used to describe an ongoing action that will not have been happening up to a specific point in the future. It combines the negative form of the auxiliary verb “won’t have been” with the present participle (-ing form) of the main verb.
- “I won’t have been living here for five years.” This sentence indicates that in the future, the person will not have been continuously residing in the current location for a duration of five years.
- “She won’t have been driving for three hours.” In this case, it suggests that at a specified time in the future, she will not have been continuously engaged in the act of driving for a period of three hours.
- “They won’t have been expecting you for three days.” This sentence implies that when a certain time in the future arrives, they will not have been continuously anticipating your arrival for a duration of three days.
Another extremely rare but listed grammar structure is future perfect continuous negative. In the iWeb corpus there are only a few occurrences:
1 WON’T HAVE BEEN LIVING 5
2 WON’T HAVE BEEN DRIVING 3
3 WON’T HAVE BEEN EXPECTING 3
iWeb won’t even allow a search for “will not” saying there are no entries!
It would seem that “English Grammar Profile” adds entries like this (point 42 in their future category) as symbolic placeholders. They are confusing though because they seem to undermine the point that they make that all their grammar points are given levels based on empirical evidence in their corpora. If there are no examples of such a point why give it a level? It makes you wonder whether all their rarer points are given a level even though there may be only a few examples of such.