Future Perfect Continuous Tense.
The Future Perfect Continuous Tense denotes that something will have done continually (often, frequently, etc.) in the future or in a (certain or uncertain) future period (of time).
A Few Models.
I will have been teaching English on the Web.
He/She will have been (will has been) learning English on the Web.
We/You will have been creating an English website.
When we want to express/stress the period [(of time) (of the action)], we use prepositions “for”, “since”, before, from, etc. and a (certain or uncertain) future time / period / expression.
Now then, the same Models become:
I will have been teaching English on the Web for years. …
He/She will have been learning English on the Web since 2020. …
We/You will have been creating an English website before/from 2022. …
Homework.
Find some more illustrations and make/line/remember the Syntax (as in lessons no. 76).