The sheer and overwhelming size of the acquistion means Nintendo may yet find their hand forced in some areas, especially if larger companies become interesting in buying up long-term partners in Japan. In that scenario, I don't think we'd see Nintendo immediately jump at large-scale or immediate acquisitions or mergers, but would instead simply up their stake in Bamco or Koei-Tecmo or whoever seemed to be the target of a takeover. Nintendo can make it difficult for other publishers or tech companies to buy the large Japanese publishers without actually pursuing mergers or acquisitions themselves. The status quo in Japan suits Nintendo, after all.
As for other independent companies, Nintendo would either prioritise long-term partners who might find themselves the target of a takeover, or they might targer partners who offer particular expertise Nintendo could make use of. In the former camp you have studios like Grezzo, Good-Feel,
potentially Platinum, and Camelot Software Planning. In the former camp I'd argue you have a company like Velan Studios, who might be a good fit for Nintendo given their work on augmented reality games. Even in the event that Nintendo began to lose some of these development partners, or risked losing them to acquisitions, outright acquisition isn't the only move Nintendo could make - they would be more interested in the people within these companies (and the creative possibilities they offer) than owning the brand or studio itself. With Nintendo's resources, they could (as they did with NdCube) set up a new subisidiary to retain the talent and staffpower these independent companies bring to Nintendo's operations. It's not inconcievable in the future that Nintendo could set up studios to retain talent from a bunch of different places (not just the ones named above, but also from places like Ubisoft Milan or more likely Mercury Steam).
You can rule out Nintendo buying out HAL, Intelligent Systems, Game Freak, or Creatures Inc, because of shared IP ownership. In those cases, Nintendo don't need to do anything but likely keep doing what they've done with HAL and Game Freak (giving them new facilities and office space, and, if Monolith Soft's Kyoto support team are involved in Pokemon Legends, greater development assistance).
Finally, the most obvious move for Nintendo to make is the one they're currently making: expand internal development. EPD remains Nintendo's trump card, more often than not, and with two new facilities on the way in 2022 (leased space in a new building, and a new building on an existing Nintendo site in Kyoto), and with extra financial investment on the way, it seems clear Nintendo see the need to protect and expand internal development. We might also see additional investment make its way to wholly owned subsidiaries, too, which would be easier than finding studios to purchase.
Worth keeping in mind that those other businesses were Bandai's and Nintendo was rumoured to be eying up a Bandai purchase in the early 2000s. Merchandising is also an area Nintendo wants to grow.
That said, they're not buying Bamco... that's just not the reason why.
Yeah, you'd think if Nintendo desperately and aggressively wanted their characters front and centre right now they'd buy a company with media and toy production capabilities.