Ive heard Errol Spence Jr./Terence Crawford to be the exact next that Manny Pacquaio will fight... just some humor & a slight chance to be the next. Actually I dont know quite yet who are these 2 growing professional boxers. But looking at their record are very impressive and Errol Spence Jr is a southpaw type of boxer also... could he be the next manny pacquiao? 
If Manny will not heed to Mommy D's advise to retire then better fight Mayweather or Khan next, not Crawford or Spence as these guys are not for him because of skills and age. Manny is legendary but fighting Spence or Crawford this time of his career might lead to disaster in terms of medical condition in the future.