Sony doesn't need to react, they only need to continue with their current strategy of focusing on consoles and dominating MS on console:
-Even adding ABK to MS gaming division and assuming all their games continue on PS (that won't happen), their revenue will be smaller than Sony's game division, Tencent and Sony are still bigger than them
-Sony consoles have 2x the userbase of MS as they did last gen
-Merging Plus and Now, Spartacus will start having 2X the subs than Gamepass
-Sony sold over 1700 games for their console, more than any other console in gaming history
-Sony PS4 exclusives won a ton of gotys and like half a dozen of them sold over 15-20M
-Sony doesn't need to buy IP, has a ton of successful ones and frequently creates new ones
-Movies, TV shows, ports of old PC games, VR and mobile are good to grow the fanbase and generate extra profit
So I think they should continue doing basically the same they had planned to do:
-Continue growing their internal teams, adding manpower to make more GOTY candidate and winners
-Continue acquiring partners (gamedev/porting/outsourcing studios) who previously did work for them with exclusives, that may help grow in new areas or genres or that will support the main teams
-Merging Plus and Now, throw on top hundreds of games more from all their generations (even if PS1/PSP/PS3 are cloud only) and add a new tier available worldwide that would be PS Now without cloud gaming, so would include all the PS2/PS4/PS5 games that can be downloaded. So a bas Gamepass like tier
-Release Spartacus (the cloud gaming tier) on smartphones, tablets, smart tvs and open it to a few contries more
-Reveal and release PSVR2 solving many of the issues PSVR1 had
-Try to solve the chip shortages issues asap and build new factories to manufacture a shit ton of consoles once chips became available
-Release GOTY candidate games like Horizon 2, GT7 and GOWR and show the ones for H2/next year
-Release PC ports of old big exclusives like GoW and Uncharted 4 and show the ones for H2/next year (I assume Spider-Man 1, TLOU)
-Release movies and TV shows like the Metal Gear, Uncharted and TLOU ones and announce new ones (GoW, Horizon)
-Keep supporting eSports with the Tournaments feature, EVO and getting -sometimes exclusivity- on FGC games
-Release big 3rd party exlusive and sign many more
-Help the indies and their relationship and conditions with Sony (Yoshida is working on it) regarding the costs, amount of paperwork needed to publish and store visibility issues