It's been a fair while now since Twitch announced their Enhanced Broadcast with Multiple Encodes beta, https://help.twitch.tv/s/article/multiple-encodes, and this was mentioned briefly during a vMix live Show but I don't recall any mention of vMix plans for it.

While many events that use vMix for production and stream to Twitch use NDI to produce in vMix but OBS to manage the streams due to vMix's streaming being limited, it would be nice if one of the improvements to vMix would be support for Multiple Encodes to 1. encourage more usage of vMix itself to encode and not just offload to other apps, and 2. show that vMix does plan to support these modern changes in a timely manner.

Twitch even are open to 3rd party stream tools applying to work together to integrate this, and have had a form for a while to support this for those that may not already have a prior business relationship with them.