I had something happen to me of a similar nature. I was happy in my job, my employers switched half the organisation around and our manager decided to do the same to our department. In his proposed plans I wasn't even in the department any longer, the "compromise" I agreed to sent someone else instead who was happy to follow that path as it fits in with his career ambitions, but I had to take on some of his duties sold to me as a "like for like swap". It was bull, I was never in the other department so it wasn't a swap at all.
Maybe I should have dug in, but if you want a good outcome the department is being disbanded and scattered so I no doubt will be back to square one under a manager I get on great with - and she's female which is a bonus
So the moral of the story is hang on in there, don't be afraid to make a noise and eventually it may well come round full circle.