What verb tense describes the sentence "By next year Bob and Kathy will have been living together for 50 years"?

The sentence "By next year Bob and Kathy will have been living together for 50 years" employs the Future Perfect Continuous tense. This verb tense is utilized to describe an action that will have been occurring for a specific duration of time at a certain point in the future.

In this case, "will have been living" indicates that the action of living together will start in the past and continue up to a future point, namely "next year." The phrase "for 50 years" further emphasizes the ongoing nature of the action over a considerable period. Future Perfect Continuous tense effectively communicates the idea of duration and continuity leading up to a future moment, which is a key characteristic of this tense.

This level of detail in the action captures not just what will happen, but also the length of time that the action has been taking place relative to a future time frame, distinguishing it from other tenses that might be less specific about duration or context.