I think conservatism as it has evolved in the Burke/Russell Kirk tradition can indeed evolve. The philodophy is not grounded in absolutes the way classical liberalism is. Conservatives stand for the preservation of those institutions that have stood the test of time in terms of maintaining our way of life. Once enough time goes by, conservatives end up supporting liberal programs by virtue of the fact that they have become indispensable institutions.
Thus, conservatives talk of preserving Social Security and Medicare whereas libertarians would prefer to do away with them. In time, conservatives will want to preserve obamacare for the same reason.