Planned Parenthood v. Casey was a 5-4 decision.* It's difficult to imagine that whatever wingnut Bush has to offer up to please the base wouldn't flip that, and effectively overturn Roe. I doubt Republicans will actually be happy with that, the ones who want to get elected anyway, because I think they understand what Democrats don't seem to - people in this country quite strongly favor abortion rights (it's important to remember that all the laws they enacted to use as test cases have bee written in such a way to guarantee that the Court in its current form would shoot them down in order to keep the issue alive for one more election cycle). Yes, the "ick" factor causes people to embrace the curtailing of abortion rights around the edges, but that's mostly because people who are made slightly uncomfortable by the issue want to have a little bit of an "out."
When Roe goes, there will be much confusion among Democrats I imagine. The anti-abortion machine is in place and it is far stronger than the abortion rights machine. Since the media gives deference to anything under the cover of religion, and equates religion with conservatism, the anti-abortion machine will have much more uncritical treatment by the media.
When this moves to legislatures - federal and state - odds are the temptation by Democrats will be, as it generally is, to compromise, to find the center as defined by Tim Russert. To stand, then, for nothing.
The removal of the constitutional right to have a say in what goes on in your uterus will certainly be a bad thing, but it will also certainly be a political opportunity for the Democrats to define themselves, if only they seize it.
As a secondary issue I've always been a bit puzzled by those who think that the Roe decision somehow made politics nasty. When legislatures have the power to legislate this issue, it will be, at least for a time, the central issue for every candidate in every state and federal election. It will be all abortion all the time.
And, it will be nasty.
*People in comments have reminded me that until O'Connor's retirement the "pro-Roe" crowd numbered 6. So, perhaps this issue will be punted for another couple of years. Someone make sure Stevens has a good doctor.