Dunno about waiting for good animators tentens filler had some good animation and even the last episode before it did, bee's episode is looking good. Infact I garuntee Naruto and Sasukes battle will be subpar animation.
Maybe waiting it out for a new opening? Maybe they're in the process of writing Naruto GT and want it ready to go when the canon ends so it can air the week after.
1 to continue milking the series to maximize profits. 2 It's not to give the animators time to do more work. More often than not, these episodes get done a day before or the day of release. 3. There's going to be more filler to cover the 699-700 transition. Heck expect filler to cover the time gaps in 699
To predict alittle I'd say
naruto and Sasukes battle gets drawn out alittle longer maybe lasting 10 episodes
chapter 699 gets drawn out to maybe last 2-3 episodes
(maybe) kakashi novel
The last done in the anime (like BoG in dragon ball super)
the other novels
chapter 700
gaiden (drawn out to last a full season)
then naruto GT
ends the year after from low ratings