Judging by the anime industry I doubt they will make a long filler like they just did with the Chunin exams - possibly just a few episodes.
You can get a special 1 day "filler" on special occasions, like an anniversary, or as a tribute to different anime or different anime style or genres.
Otherwise we get fillers when:
Characters need development or background (not likely at this stage of Naruto)
The anime needs to let the manga run ahead (again not needed at this stage)
When the animators have the attention elsewhere, i.e. they are making a movie, and the anime don't want to produce poor quality canon material, they will give averagy quality filler episodes (e.g. when they were making the last we got the Chunin exams). As they are now making Boruto the movie (which is being released a mere 8 months after The Last - quite an achievement which we should congratulate the animation staff and Kishi for), they are working harder on that, and have the best animators on that, so they give as average filler instead of average important canon, than after the movie they give us high quality canon.
BTW: This requires no comment but please remember before complaining about filler (which is in a viewer's interest anyway) animators spend a crazily long time on animation for a crazily low pay, they are incredibly talented and we should all appreciate and admire their work.