That said, if there are things that we can do to increase privacy while still hosting Trello on our own servers, we'll certainly consider those. I never want to commit to any particular feature, but it is not impossible that one day we will provide IP whitelisting (so a given board is only available from approved IPs) or even client-side encryption. I should reiterate that neither of those features are in our near-term plans, but at least they are not completely out of the question. Having been in the downloaded software business for ten years, I can safely say though, that we are never doing that again.
It's unfortunate that there's no meeting in the middle.
As an aside, I suspect a few of the companies who, in the past, could "never" use software that wasn't installed on their own systems are probably using Salesforce now.