From Longman Dictionary of Contemporary English(just) you wait(just) you waitspoken a)  British English used to warn or threaten someone I’ll get you back for what you’ve done, just you wait. b) used to tell someone you are sure something will happen It’ll be a huge success. Just you wait. → wait
                                                    
                                                Examples from the Corpus
(just) you wait• It'll be a huge success, just you wait. 
