Depends how good the Sw/Sh DLC is honestly. If it's actually significant, gets marketed well (and possibly even a digital bundle with a new copy of the game? Game + DLC for $75 or something?) then I can see it boosting Sw/Sh sales to stay past BOTW and finish up around 26-27m LT.
If the DLC is forgettable, like the games themselves were to many, then the boost will be negligible and BOTW will take this LT.
BOTW is looking at 21-25m LT depending on when 2 launches, either way this will be close.