Earlier quoted context omitted.
All Blizzard game have online features, they never shutdown an online game, never, Diablo 1 is still running since 1996. I don't see issues with online only tbh.
No, the Lost Vikings for instance don't. And last I checked they seem to have given up on supporting Diablo 1, and let GoG deal with it instead ? (Its online MP has security flaws.) And Blizzard cannot run a game if Blizzard doesn't exist. But even before that happens, you can already see the wasted potential : D3 (and D4) has no modding whatsoever, compare with D2R (though mods there are still heavily restricted and…
lost vikings is not a blizzard game, and they still run diablo 1 matchmaking it's not gog.