depending on the game you can. try Steampowered dot com. it's not streaming the game but it's the same idea.
PC has the potential to destroy both xbox and PS.
But they don’t want that. Because consoles are made for games. If people can play games elsewhere they become useless and obsolete. Consoles are trying harder to be PC.
There isn't a PC in the world fast enough to run a PS4 emulator, but a lot of games will also be released for PC as always.