He (would, might) have gone abroad

[keannu]

Can we say "He would have gone abroad" in this case? "would" is a stronger certainty than "might", doesn't it make sense?

ex)I haven't seen Jack for years. He (would, might) have gone abroad.

[JohnParis]

Keannu,

Might.
For, basically, the same reasons as in my previous post.

John

[keannu]

Keannu,

Might.
For, basically, the same reasons as in my previous post.

John

ex1)A : We invited some celebrities to our party tonight
B : That would be fun.(presumption)
I think "would" has the meaning of presumption as in the above example, but maybe in the past form, it's used as a part of conditional meaning either presumption or counterfactual element.
ex)A: We invited some celebrities to our party last night
B :Wow! If I had gone, I would have seen them!
Doesn't this "would" have any kind of presumption?

By the same token, I roughly guessed,(though I was a little confused), "would" in "He would have gone abroad" has the meaning of presumption. Is it only conclusive utterance?