Some extra related take: when a company like MS or Sony acquire a big 3rd party publisher is to secure their content for their consoles and game subs, but mostly to get the revenue and profits that acquired company already makes selling games and addons in all platforms.
They try to maximize that revenue and profit, in addition to having it on top of what they already had instead of growing organically (organic growth = improving revenue mostly by mostly improving and growing exising products and services instead of growing mostly via acquisitions).
Meaning, they will want to keep them multiplatform, because turning them exclusive would mean to stop getting a huge portion of that revenue and profit of the company. To making all their games exclusives would mean they'd get way less revenue and profit from that company, and pretty likely many of their games would stop being profitable.
In addition to this, these acquisitions -as mentioned multiple times by Sony and MS- are part of their multiplatform strategy: due to console not having grow enough compared to the AAA budgets and growth of each console brand being also limited, they need to expand beyond console, so they aim to grow also not only in rival consoles, but specially in bigger markets which are PC and mobile.
So if Sony or MS acquires big publishers, don't expect them to stop releasing games in rival consoles, and even less in PC or mobile. In fact, they'll make them release more games in more platforms to make them generate more money.