Excellent news.
Happy to see that the vision of one global game for the whole content is finally coming to life 
Let’s just hope that it will not make complications regarding access to legacy content (HITMAN 1&2) and transferring account data from one game to another 
Also, since it’s supposed to be the whole game on one roof it would be reasonable to bring back all missing content from previous games (Missions, tools, weapons, …) so we don’t have to go back and forth between games to have the whole content 
What is also confusing at the moment is how you are going to manage all of this…
Is it a newer version of HITMAN Trilogy or are you just rebranding HITMAN 3?
I think that removing HITMAN and HITMAN 2 from stores is a bad idea unless you are going to merge everything into one roof for the best.
There are things that i prefer in the first game and others that i like in the latest installment of the trilogy. Restricting the whole trilogy into only one available game would be wrong as there are lots of things that differ from one to another, especially gameplay features!
Putting everything into one roof will mean that players will have no choice regarding gameplay mechanics, graphics, missions, weapons and tools, but also 47’s face.
So much things differ from HITMAN (2016) to HITMAN 3 that it is a high risk to propose only one version of the game without checking the ensemble before that 
Maybe put this standalone version of HITMAN as the ultimate update of the trilogy but as another game instead of only renaming HITMAN 3?
→ HITMAN (2016): only one version (full pack)
→ HITMAN 2 (2018): same (full pack only)
—> HITMAN 3 (2021): complete pack
So no more (or much less) confusions about purchasing. Then:
----> HITMAN: WoA (with updates and discounts) | a.k.a the actual “HITMAN: Trilogy”
With eventually the option of either selecting a standalone game (as a legacy preservation) OR using HITMAN 3 mechanics for the whole stuff…
We’re one step closer to perfecting the HITMAN experience anyway.
Wishing the best to developers still working on that beloved franchise
Check also (for deeper insight): A different (and better?) way of bringing the WoA into life.