This is the situation my sister is in. Last spring she accepted a deal with her company to move halfway across the country to help open a new branch office, in exchange for a promotion to Manager and appropriate raise.
Yesterday the CEO announced a total reorganization, shuffling job titles and everything. There is no longer a "Manager" tier. My sister's title is now Account Executive (she had been Inside Sales before), and she is no longer supervising anyone; "Directors" are now supervising everyone in the branch offices.
She doesn't quite know how to feel about this. They didn't reduce her pay. But a large part of her reason for agreeing to move was the leap from individual contributor to Manager. She says, "I could have been doing this job without leaving home."