There is widespread agreement on the need for architectural change in the Internet, but very few believe that current ISPs will ever effect such changes. In this paper we ask what makes an architecture evolvable, by which we mean capable of gradual change led by the incumbent providers. This involves both technical and economic issues, since ISPs have to be able, and incented, to offer new architectures. Our study suggests that, with very minor modifications, the current Internet architecture could be evolvable. Categories and Subject Descriptors: C.2.1 [Network Architecture and Design]:Network communications General Terms: Design.