I don't know how many times I've been asked that question, or attempted to answer it. The short answer is fairly simple. We have the technology to support interoperability today in our hands. Not everyone agrees on what it is, but it does exist. Even those of us who don't agree on which technology to use can still use it even if we don't like it. The real problem is not the technology, but rather in its deployment. It takes a lot longer to get the technology into the healthcare provider's offices than anyone really wants it to.
You can argue about whose fault that is, and no matter which argument you choose, there's probably some truth in it. It takes time. We will get there. This is not a technology problem.
One thing that I've observed happen more than a dozen times since I got started in this field is that you can solve the technology problems in 1/5 the time it takes to develop and agree to the information sharing policies. I've seen that happen over an over again. It's not about bits and bytes. That's the easy part.
The time is really about the words on paper that wind up having to be approved by the lawyers and signed by the big bosses.