For Nintendo and Illumination, it means the partnership will likely continue on. During an interview with Screenrant, Nintendo's Shigeru Miyamoto confirmed this - mentioning how he was "sure" the two companies would stick together going forward.
Illumination CEO and founder Chris Meledandri reaffirmed this, going on to describe the partnership with Nintendo as "a really rewarding collaboration". He also noted how he had previously been invited to join the Nintendo board of directors and said the companies were already "working together into the future".
If you've already seen the Mario Movie, this news probably isn't a surprise that there's more to come, but it also means there could be much more than just Mario on the horizon.
Although Miyamoto and Meledandri both seem to be interested in working together again in the future, right now they agree there's "nothing" they can really share at this time about any other Nintendo themed projects.