Hector Martin

I'm pretty sure you can implement it in a firmware update for most devices. Whether manufacturers will bother with legacy devices is a bigger question. Nothing here needs new silicon.

Odds my mid-90s synth gets updated: 0%

We could reasonably bet, as long as manufacturers will still make the effort of installing DIN plugs into MIDI devices, legacy MIDI will continue to be supported. In the pro world I'm not too afraid for now. In the consumer/soho range of devices, that will be another story

Hector mentionned a compatibility layer in this thread. So even if your device is using USB transport, there is still hope

I get the feeling DIN links are going away and being replaced by USB as the default standard.

For devices designed to be connected to a computer, definitely. For studio gears that you may daisy chain, we still have DIN links. At least, this is what I see in the few studios around here. But I wouldn't claim this is representative of a trend, nor of the state of the art.

For full disclosure, I'm not an audio engineer, even less a MIDI expert. I'm just an (enlightened?) enthusiast lucky enough to hanging around on pro studios once in a while. Take my comments with a (huge) grain of salt!