My understanding is that the sentence
I will have played tennis.
is future perfect.
But, what happens if I substitute the word "will" with a modal such as "could" or "ought to"? Does that change the tense? If so, what tense is it?
For example, what tense is the sentence
I could have played tennis.
Does a similar mechanism come into play for the sentence
I will have been playing tennis.
(future perfect continuous) vs.
I could have been playing tennis.