From a purely business point of view, to combine Hytale and VS into a one paid product would be a legal nightmare, it would force Tyron to either arrange for transaction of IP for all developed resources or cause the VS team to re-make Hytale in VS assets. above all else, there is merit to the "we paid for VS, not this" argument, Early access game devs do this far too often, and if the other horse looks prettier, why focus on your first. or at least that's the view point seen when both are actually off to the races. to wit, if Hytale is more appealing to a general community after joining the VS fold, we could easily see a reality where VS falls to the wayside, and that's not what a current majority of us are purchasing the game, or continuing to support the devs for. with that, the opportunity for IP arguments would only skyrocket if popularity goes up after this. If Tyron is willing to extend this nuclear olive branch, he'd better be wearing some lead gloves and have an incredibly solid plan.
none of this touches what would be required of existing users, if Hytale has networking built in, and is added to existing update pipelines for VS, it requires a re-work of TOS. I wont lie, I likely wont be willing to agree with it, and that would be the end of my time playing VS if provided no option to opt out and stay on the current build.