future perfect progressive

1. the form

1.1. will have +been +V3

2. note

2.1. sometimes either the future perfect or the future perfect progressive can be used to express the same

3. example 1

3.1. by 2025 people will have been flying for 122 years

4. example 2

4.1. by 2020 i will have lived in Sao Paulo for 15 years