How to be nimble, agile in the face of changing technologies?

Hi Folks,

Suppose that in the future the tide shifts and the XML world moves en masse away from XML Schema to Relax NG (or some other simple, powerful language with a strong formal basis).

Let's assume that validating XML instance documents is required.

When the day arrives to shift to Relax NG I wish to make the shift with minimal breakage and cost.

How can I design today so that tomorrow I can nimbly change to a new validation language? Are there concrete, practical things that can be done today? Perhaps one thing that can be done is to require every data model be implemented in both XML Schema and Relax NG. What else?

/Roger