IOI is working on Project 007 (a James Bond game) and Project Fantasy (an online fantasy RPG), they simply don't have the manpower or the resources to allocate to Hitman right now.

The Hitman series won't have a new game for quite some time, considering WOA will still get content updates up until at least the end of this year from a skeleton team of staff that is slowly dripping content such as items, weapons and suits that are present in the public game files.

Hitman 3 is the end for now. You're looking at 007 probably in 2025.
It was announced a long time ago, you've missed it probably.
https://youtu.be/m4rU_TTn7EE