Let’s not worry about the sky falling when there hasn’t been a single announcement that NavBlue maps are being forced upon anyone.
If you allow me to make a guess; I would guess that NavBlue will be implemented as the standard maps provider, seeing that MS/Asobo have a contract with them (and thus will be free to use for all sim pilots), and that users with a Navigraph subscription will be able to inject those, just like you can inject Navigraph nav data into the sim right now.