Your example is not future subjunctive. It's not subjunctive at all, in fact. It's conditional.
The closest English comes to a truly future subjunctive mood is using the future periphrastic in conjunction with the past subjunctive mood, for example:
- I wish we were to ski in the Alps rather than the Andes for the finals.
- I wish we were to be skiing in the Alps rather than the Andes for the finals.
Combining the infinitive with the subjunctive casts the action definitively into the future.
Remember, the monikers present and past in English verb conjugation regarding the subjunctive moods refer to the form and not to the time of the action expressed as the events are merely hypothetical, an irrealis. In reality, the event's aren't happening and haven't happened.
What you have is an instance of the perfect continuous conditional. The subjunctive clause that brought the condition to fruition remains merely implied (e.g., 'if you had got everything ready as expected', 'had you done what little you'd been asked', 'were you not a complete and utter numpty', etc.)