Microsoft pulls off an unusual move as it begins testing an update of Windows 10 that won't be out until 2020. The company isn't known for testing out updates this far out in advance. Microsoft usually does two updates per year, and it hasn't started testing the next 2019 update yet. However, it seems this new 2020 update needs more lead time.
According to Microsoft Windows Insider Chief Dona Sarkar, this update requires a longer testing period. But Sarkar didn't specify what 20H1 update will include. Beta testers who opted into the Skip Ahead ring for future Windows versions will start seeing this update (which is labeled as Windows 10 build 18836).
Source: The Verge