It seems that any additional content for The Legend of Zelda: Tears of the Kingdom might not be quite as set in stone as we initially thought after a recent Famitsu interview with series producer Eiji Aonuma and director Hidemaro Fujibayashi seems to suggest that Nintendo currently has no plans for DLC.
Right from the get-go, it is worth bearing in mind that we are currently only able to read Famitsu's interview via the built-in Google Translate function, so there is a chance that the point of Aonuma's response has been somewhat lost in translation. That being said, the series producer's answer does seem to imply that TOTK DLC is not currently a concern for Nintendo.
The point in question comes from the end of the interview, where Aonuma and Fujibayashi were asked what they are working on next. The director suggested that he doesn't currently know what form his follow-up project would take, though Aonuma gave the following, more Zelda-related response (via Chrome's built-in translate tool):
Aonuma : There are no plans to release additional content this time, but that's because I feel like we've done everything we can to create fun in that world. In the first place, the reason I decided to make this a sequel to the previous work was because I thought there was value in experiencing a new game in that Hyrule place. If that's the case, if a new reason arises, we might return to the same world again. Whether it's a sequel or a new work, I think it's going to be a completely new game, so I hope you're looking forward to it.
There is a chance that the series producer is referring to another game set in the same Hyrule as Tears of the Kingdom and Breath of the Wild, though the context of the rest of the answer does seem to suggest that the "additional content" in question is DLC for Link's latest.
This undoubtedly comes as something of a surprise — BOTW was treated to two different DLC packages after all — though the sheer size of Tears of the Kingdom does beg the question of what its DLC would even look like.
Unless we see some clarification in the future, we can assume that no TOTK additional content will be coming our way for the time being. It's a shame, for sure, but we suppose it's as good an excuse as any to finally clear that remaining 70% of Hyule that has been staring at us for a good few months now...