Changes to my job description, how should I approach?

My boss has talked to me about changing my work description and basically leaving my current position for another one. She wants my feedback on the proposal but the ';changes she's proposing'; really originated from a co-worker. These changes entail consolidating positions and my co-worker effectively replacing me. I don't think it's a good idea regardless of being phased out. But I can't change jobs right now so I don't want to antagonize my boss. How would you best approach the situation? I can give further details if necessary. Thanks!Changes to my job description, how should I approach?
This is not an easy one. I think the best focus is to create a job description that you feel ok about. Try to have some influence on what is decided. When you talk with your boss tell her what you would like-she asked for your feedback. Stay away from bad mouthing your co-worker. Keep it strictly about the work you want to do. You may be able to influence your boss.

Never let yourself feel trapped. Do your best to create a good outcome, but if it doesn't go your way, you always have options. Good luck.