Student or Learner
"He will have gone back by the time I reach here with my horse". Can I say "He may/might have gone back by the time I reach here with my horse?".
I am walking.
So you will be walking? (The phrase "by the time I reach there with my horse" suggests that the horse will be led there and will not do overmuch work.)
I am asking about future tense. I am not sure whether he will be there or not by the time I come back. I am not sure about the situation. So can we use "may/might have done" in this kind of future tense depiction?
Yes, you don't have to use 'will' for the future if you're not sure.
"He might/may have gone back by the time I reach here with my horse" also works for the future.
You can also solve the problem of the modal verbs by using adverbs with "will", but you can't use "will" alone, unless you are sure.
"He will possibly have gone back ..."
"He will likely have gone back ..."