Server computing: Open source is currently winning, it will probably keep winning.
The Desktop: Open source is fully usuable, however only a small percent of market share. Might be the future if wine and proton keep seeing major imorovements.
Mobile phones: Open source isn't winning (I wouldn't really count android as open, but that's up for debate). I don't see open source being the future here anytime soon, though I truly hope it makes it.