This sentence is incorrect. 'Come' is used with 'here', 'go' is used with 'there'. At best this sentence should be "I will have arrived there"
Agreed it's not quite right. 'I will have gone there' could work though.
It's a little off in English, but different languages make different distinctions between "here" and "there" and between "come" and "go". Greek definitely uses "this" more than "that". I'll assume the Greek is fine as it is.
"I will have come there" does not sound good at all
how about "arrived"?. I'm thinking about how the elevators say they're coming and then say they've arrived.
I agree with the previous users, in that this sentence is wrong in English, but what Robert says above is correct:
"I will have arrived there."
One could also say:
"I will have gotten there."
« I will have come there» does not sound natural . «I shall / will have got there» flows more easily.
If you still wanted to use "come", try this: "I will have come from there".
Then you need άπο εκείνο