1. Technically you still have to buy the game to play medianxl
2. Depending if the game still kept the old spreadsheet format or they changed
3. Sigma already modified codebase of normal cLoD, so it cant be bring to resurrected 100%
4. Im sure i saw somewhere about modder support, although i dont think it will be to a point where they will promote it in the game.
5. Matching data from the mod to 3d effect will be huge task as well.
at least they how i understand how resurrected & sigma was developed, it will not be easy plug & play as you thought
can take couple of months or years.
probably some simple mod will come out first (the one that only modified spreadsheet)
a drop mod alone might be fun
just take note that blizzard is still keep the multiplayer system like before.
closed battle net (data stored in their server) and local single player
I have no idea who have control for tcp/ip (i dont think they will keep this) or open battle net though
they dont want the server to be filled with bots and hacker after all
Added link to all info you need from official tweet here : https://twitter.com/Diablo/status/1362937581177077767
Why you would want to manipulate this Hell? Are you some sort of demon yourself? Woe! Yes, mod support will be here in Diablo II. I beg of you to go easy on a poor old man.