Rocky's comment on the article at enterprise-architect.net is spot on. The main tenent in SOA is that we can assume very little about the services we interact with.

The only thing that is shared between services is the contract. Making assumptions at build-time beyond this, are bound to limit the usability of that service later on. Trying to change an existing system so that it can cope with a distributed scenario, seems similar to adding other fundamental features like security.

When done as an afterthought, it will take dramatically more effort and it will also be more prone to inconsitencies in it's implementation.