The 78-year-old singer thinks the time could be right for the two stars to put their differences aside after so many year and put the iconic Motown group back together one last time with Cindy Birdsong.
Duke - who is the last original surviving member of The Four Tops - told BANG Showbiz: ''I'm going to make a prediction; somewhere down the line I see her and Mary giving each other a big hug and saying, 'Let's do this one more time.' The older you get as you look back, whatever happened in those bygone days is forgotten - usually. Why not? I kind of feel that might be coming up. I think they might do one big concert or it could be a residency in Las Vegas or somewhere like for a week or so. It's very possible, I just see that happening and it would be great.''
Duke - who is currently on tour in the UK with his group and The Temptations - is convinced that Diana, 70, is ready to bury the hatchet with 70-year-old Mary and knows she is ready to perform because she regularly performs, describing her concerts as ''fantastic''.
Temptations star Otis Williams is also hopeful for a reunion and insists the 'Baby Love' hitmaker is in a position where she can play just to cement her amazing legacy.
Otis, 72, said: ''Oh Mother Supreme, as I call her, is still playing. She's in a unique position where she can keep playing and work when she wants to work.''
Mary turned down the chance for a reunion tour as The Supremes in 2000 after she discovered Diana was offered $15 million to do it, whilst she was offered $4 million and Cindy less than $1 million.
The last time Diana and Mary appeared on stage together was on the 'Motown 25: Yesterday, Today, Forever' TV special in 1983.
The Temptations and The Four Tops - joined by special guests The Platters and Freda Payne - are playing concerts across Britain this week, including Manchester Arena tonight (02.04.14) and The O2 in London on Thursday (03.04.14).
Without giving away any spoilers, both the British actors hinted that season seven of 'Game of Thrones' would be eventful, shall we say.