I hope someone can help me, please.

This error was included in a present continuous lesson.
'John has been to Paris - I expect he'll come back next week.' However I am wondering what rule there is for present continuous? How could you correct this?
If John is currently in Paris and you know he'll return next week. Why use present perfect?

They've mixed Present Perfect 'Has been' with future tense 'He'll come back'
Would it be correct to say 'John is staying in Paris - I expect he is coming back next week. Can anyone help me decipher the rule here?
How else could you say that John has been to Paris and he'll come back next week.
Thank you in advance.