It'd also be nice if the iOS or Chrome client had a chat history backup feature like they have on android. This is one of my biggest complaint with messaging apps in general. I'd like to be able to preserve and archive my chat history with people close to me.
This is also why Data Loss Prevention software is truly useless in an employee environment. Sure it can spot you forwarding email, but I can take a picture of the email with my phone.
You can't trust the client. It's the same fundamental flaw with DRM. If that person does not want it archived, you can make it difficult but not impossible.
Actually, I can get the source code for the client, delete the "auto expire" feature and compile it. So there's nothing stopping anyone from archiving messages you want them to be able to read.
This issue is one of those that make it very difficult to build a single "secure chat" app that does everything for everyone.
Personally, I want an automatic, encrypted network backup of all my messages so I don't lose them if my device is lost or destroyed. But I know lots of folks around here are excited about the automatic delete thing too. It's going to be very hard to make something that all of us can be happy with.