Yes it was a theory that hamara gave his power to hagamaro before they sealed the Juubi/Kagaya. Wow a lot of theories are coming to light.
Pretty sure Naruto parallels Hagamaro and Sasuke parallels Hamara. If the parallel is 100% accuarate Sasuke may sacrifice himself for Naruto can seal Kagaya again. Then that would prove someone else theory correct about Sasuke sacrificing himself.