Yeah, Sony's best move with Capcom would be to purchase as many shares as possible into the company, get a person or two onto their Board of Directors, and provide financial investments into the company for various projects & initiatives. Everyone gets what they want in that case and the company as a whole is significantly less likely to merge or be sold for acquisition.
Really the only publisher Sony should prob immediately consider to buy is Square-Enix. Even there, they could just pump a lot of investment into specific development studios at Square-Enix, buy shares, fund development of co-developed new games (like a remake for Parasite Eve; that game deserves a lot more love) and even fund initiatives like anime based on Final Fantasy & Dragon Quest. They don't actually have to buy Square-Enix, and can get almost all of the same benefits (minus rolling Square-Enix's revenue and profits into the PlayStation unit's) anyway.
In that sense, they would be better off buying smaller to mid-sized developers first but, in this case, some with actual published games as a studio. Stuff like Level 5, Arc System Works, Vanillaware, Ember Lab etc. And then leveraging those devs to work on mixture of AA-sized efforts (with new & legacy IP) and work with IP and dev studios of 3P publishers Sony makes strategic investments in, for new & legacy IP, creating exclusive content for PlayStation (and in some cases, also for PC).