We are getting closer, and are still working thru some bugs, but hope to release this as part of a Public Preview pack in early 2021! (Windows 10 released with the December 2020 pack this week)
You can learn more about the new Microsoft Teams Public Preview program here: https://aka.ms/TeamsPublicPreview, and Teams administrators can find documentation to manage which users will see the Public Preview option here: https://aka.ms/TeamsPublicPreviewAdmin
The engineering team is continuing to work on adding support for multiple accounts on desktop clients. We will first launch support for 1 work/school account and 1 personal account so users can enjoy Teams for work and personal side-by-side. Windows and MacOS. Support for multiple work accounts is still being worked on and will come at a later date.
You can track status via the roadmap here: https://www.microsoft.com/microsoft-365/roadmap?searchterms=68845.