that says support for it stopped from v4.4+, will that be changed or goodbye to custom gate numbers?
That thread said exactly the opposite: support for jetway numbers STARTED with P3D 4.4, not stopped. They never worked with FSX, P3D1, 2, 3 or any version of 4 before 4.4. It works with 4.4 and 4.5.
P3D V5 is an entirely different matter, as explained in the thread linked by Captain Kevin, because it requires rewriting all our support code that used DirectX11 in DirectX12, since there's no support for DirectX11 in P3D V5 anymore. At this time, we don't know exactly when we can add this, because there are still some stability issues in V5 that makes the Render To Texture function not fully usable yet, it will likely require another Hotfix from LM first.