I think I would be upset, just as I am upset with Avril's change. I wouldn't be angry, but I would be sad with a sense of loss. With that said, I would never abandon her as a fan, just as I have never abandoned Avril. I continue to support Avril (in hopes of a rediscovering of roots a la after Jewel's fourth album) as I would continue to support Vanessa, should she make the decision.
I feel exactly the same way.
If she changed, I would feel like there's no more hope in the music industry for real artists. I'd still buy her albums though, because her music has really touched me and helped me through crises and I don't think I'd ever stop hoping it would come back. But I would be really upset and kinda feel betrayed. That sounds stupid - I don't even know her. But maybe betrayed by the music I came to trust, rather.