The future perfect continuous, also sometimes called the future perfect progressive, is a verb tense that describes actions that will continue up until a point in the future. The future perfect continuous consists of will + have + been + the verb’s present participle (verb root + -ing).
When we describe an action in the future perfect continuous tense, we are projecting ourselves forward in time and looking back at the duration of that activity. The activity will have begun sometime in the past, present, or in the future, and is expected to continue in the future.
Nonaction Verbs Do Not Use the Future Perfect Continuous
Remember that nonaction verbs like to be, to seem, or to know are not suited to the future perfect continuous tense. Instead, these verbs take the future perfect tense, which is formed with will + have + past participle.