I think an image change-up was inevitable for Rih with her GGGB album.
"Umbrella" undoubtedly propelled her to the front-line of the Pop game, but if it weren't through "Umbrella", it would have been through another single - she was already well on her way to the top even before 2007.
So, I don't think it'd change much. Rihanna would still be where she is today, one way or another.
She would still be popular and relevant. But if Umbrella wasn't released people wouldn't say she sold her soul and ****ed around with Jay-z. That's the only thing that would be different.
1. Mary J. Blige would have released "Umbrella" instead and she would have been in a much better place than she is now.
2. GGGB sales wouldn't have been nearly as high.
3. They would released something absolutely ridiculous as the first single. "Shut Up & Drive" or "Rehab" come to mind.