À bientôt. Un jour, je ferai peut-être en sorte qu'on se rencontre vraiment par hasard.
The phrase "faire en sorte que" conveys the idea that you intentionally see to it that something definitely happens, correct? The use of "par hasard", on the other hand, indicates that their next encounter is purely coincidetal – something that happens by chance.
Making sure that a chance encounter will definitely happen? These two ideas do not seem to mix. Is this apparent contradiction meant to be ironic?