Right now Sony is still doing well because they are riding on the success of the PS4, while Microsoft's new studios and publishers are still developing their new AAA games.
As soon as Microsoft's 1st party studios are ready (2023), it will be the beginning of the end for PlayStation as a platform. Xbox will be everywhere with the help of Xcloud. Consoles, TVs, Mobile, Tablets, PC... maybe even on your toaster. You only need a controller. Sony is still struggling with their cloud strategy and their mediocre services.
Microsoft is buying publishers! Publishers including famous IPs. Not some small random no-name studios like Haven or Savage Game Studio.
Microsoft will own some of the biggest gaming franchises ever. No matter if it's Minecraft, Call of Duty, Warcraft, Starcraft, Diablo, Overwatch, Elder Scrolls or Fallout. They own some of the biggest studios and publishers that ever existed. Microsoft pretty much dominates the whole WRPG and FPS genre. Minecraft is still the king for the kids.
Meanwhile you have Sony with some mediocre 1st party studios like PixelOpus, London Studio, Media Molecule (Dreams is a 10-year-failure), Valkyrie Entertainment, Haven, Asobi Team, San Diego Studio, Nixxes, or Firesprite.
If you're honest you will admit that PlayStation Studios only has 4 relevant/succeesful AAAstudios. Naughty Dog (Uncharted, TLOU), Santa Monica Studio (GOW), Guerrilla Games (Horizon) and Sucker Punch (Ghost of Tsushima).
The rest of them are some unsuccessful AA studios like Housemarque or Savage Game Studio disguising as AAA studios. Or some random port/remake studios like Bluepoint, Valkyrie and Nixxes no one gives a shit about. And Polyphony is a joke compared to Turn 10 and Playground Games.
Of course there is Insomniac Games who's struggling to create new successful AAA IPs, so they have to work on foreign licenses (Marvel Spider-Man & Wolverine) to be succeesful.