That is the intended roadmap for Working Title Garmin code modifications (note code modification, not Community Mod, not Add-On) - it will eventually be integrated into the base sim core code. If you’ve tried either the CJ4 Mod or the NXi free download in the MarketPlace - then you’ll know what you’re asking for is what you’re going to get. VNAV works in both - today.
In the meantime, feel free to participate in the NXi thread or join the conversations in the Garmin and NXi Early Access Channels on WT’s Discord Server: