I don't see them buying up some AAA publisher like Microsoft just did.
That said, a smaller studio could be in the cards. No publisher since Nintendo seems to largely prefer using it's own IPs to those from bought studios (apart from Bayonetta of course)
With that said, If I had to choose some studio to buy, it would probably be WayForward games, as Shantae, Mighty Switch Force and Vitamin Connection really fit well with Nintendo's own IP in my opinion.
The Nintendo eShop rating Thread: http://gamrconnect.vgchartz.com/thread.php?id=237454 List as Google Doc: https://docs.google.com/spreadsheets/d/1aW2hXQT1TheElVS7z-F3pP-7nbqdrDqWNTxl6JoJWBY/edit?usp=sharing
The Steam/GOG key gifting thread: https://gamrconnect.vgchartz.com/thread/242024/the-steamgog-key-gifting-thread/1/
Free Pc Games thread: https://gamrconnect.vgchartz.com/thread/248138/free-pc-games/1/
