[microcolonel]

I've been trying to figure out what it would take to make SMTP the last business IM protocol. Today's fancy email applications are basically laid out like IMs anyway. It just seems like a matter of getting delivery latency down, and demanding some level of compliance with modern email standards (STARTTLS only, must have spf and dkim, must have FCrDNS). If we're playing by IM rules, we can even have people establish contacts, which should make spam filtering a lot lower latency.

The other sundry things would be video transcoding, and reference-type attachments (for stupid nonsense like attaching a giphy to your message, or possibly-useful things like embedding google docs info).