Will there be a Scenery/Airport Gateway project like Xplane?

[Trainplane3]

They did release the tools. The SDK is available to install from within the sim:

[HOW-TO] Getting started with the SDK / Dev Mode

Step 1: Turn on Developer Mode using the General Menu. This will turn enable the additional menu bar at the top. [SDK Dev Mode On] Step 2: Install the SDK by going to the help menu and selecting SDK Installer [Installer] After the MSFS_SDK_Installer.msi file downloads, open it. [SDK Install] Step 3: Locate Documentation folder [Folder] Step 4: Open the compiled HTML file (.CHM) [Index] Step 5: Create!