Instead of retiring outright to give Wlad a shot at unifying all the belts, he should make some deal with the WBC for Wlad to get a crack at his belt, vacate, and then target the WBA "regular" championship which will be created when Haye is declared super champion. This would leave Wlad as the undisuted champion (providing he gets the WBC title) but Vitaly will still have a powerful magnet to attract former champs like Haye, SNV, and Chagaev, and young contenders like Povetkin and Helenius, who will have nowhere else to go accept Wladdy. All these names would add to his legacy.
The WBC is going to try and let Arreola fight the easiest opponent available for the vacant belt when Vitali steps down wait and see...