As noted in recently submitted public court documents, the previously reported deal for Call of Duty on Nintendo systems also includes other Activision Blizzard content.
Nintendo is mentioned a lot in the documents, but the key part that suggests we could see games such as Diablo IV on the Nintendo Switch (or a successor thereof) is as follows:
"The Nintendo Switch is not only more popular than Xbox overall, but Nintendo has a contractual right to obtain Activision content post-merger"
While the Call of Duty news is bigger, given that a Nintendo system hasn't received a new Call of Duty release in quite a while, this is also something worth noting. What it essentially means is that we could realistically see any potential future Diablo release on Nintendo platforms, along with games such as Crash Bandicoot, Spyro, and Starcraft now on the table as possible Nintendo titles.
What ISN'T specified in the documents, however, is whether or not Xbox has to commit to making a version of every game for a Nintendo platform. It could only be games that can already work on both Nintendo and Microsoft platforms that are part of the contractual agreement, but the agreement could also mean that Microsoft and Activision Blizzard have to go to great lengths in order to get something running on a Nintendo system, which is historically lower-powered than anything coming out of Microsoft and Sony.
We already know thanks to previously announced deals and statements from Phil Spencer that Sony will be receiving Call of Duty for an unspecified period of time, though Axios has reported that the deal is currently also ten years, as with the Nintendo deal. This deal however completely excludes any other Activision Blizzard titles, meaning they will only be brought to PlayStation systems on a case-by-case basis.