I'll tell you that it would really-really surprise me if the supplier will be Yanmar. JD has a lot of power to dictate, and I doubt if they would be happy with Cub Cadet selling cloned CUT's to their own lineups. I just can't see it happening with the relationship JD and Yanmar have had for that market for the past couple of decades.
Kawasaki planned on offering up lawn and garden equipment about the same time Honda and Yamaha (for a short period of time) did. JD's answer to avoid foreign takeover of that market was to approach Kawasaki as a contract engine supplier if they would not make or market L+G equipment in the USA. This tactic worked well, as Yamaha quickly dropped out of the L+G market and even Honda has dropped their L+G tractor line recently to exclusively supply engines. JD has supplier leverage due to the volume of machines they sell.
One thing with Yanmar and Misubishi as suppliers has also been the strength of the Japanese Yen. With it's dollar comparison, it almost makes no sense to outsource compact tractor manufaturing to Japanese companies as the cost of building and importing the Japanese machines is now right on par with simply building them in the USA. This puts Chinese, Korean, and Indian tractor manufacturing companies in the strongest running as overseas builders for Cub Cadet SCUT/CUT's that can beat the prices of JD/Yanmars, but as witnessed by many the quality just won't be there for the cheaper price. If Cub got the leverage against JD with Yanmar to build a quality tractor at a fair price under their badge, I think it would make many ecstatic.
As so much of the USA computer software and engineering work is heading over to India these days, and yes Mahindra is building their own tractor designs under their own roof now and has USA establishment and a decent dealer reputation, I'm putting my cards on the new Cub compacts with them. Anyway, we get to see the newbies in a few weeks

From Mahindra compact tractor site:
"The division's plant at Kandivili (a suburb in Mumbai) is today the single largest facility in the world with all tractor-manufacturing activities under one roof. The division has been the market leader for over 20 years in the highly competitive domestic market and is, currently, the fourth largest in the world in terms of units sold."
-Fordlords-