We are currently 67 chapters into this final Arc and counting an average of 3 manga chapters/1 anime episode, there is currently material for roughly 22 anime episodes.
Hopefully the anime will continue when there is enough material to restart the anime, without risking it catching up to the manga.
Let's say the anime were to resume on sep 9th, just like the manga and we estimate an average of 3 manga chapters/1 anime episode, then here are the conditions:
- Releasing 1 episode/week would cause the anime to catch up to the manga in just 33 weeks (2 chapters/week), hardly enough time for Kubo to finish the final Arc.
- However if they were to release 1 episode every 2 weeks it would take 132 weeks, or 4 times longer, to catch up to the manga (1 chapter/2 weeks); giving Kubo to late March 2016 to finish the final Arc.
So with a schedule of releasing 1 anime episode every 2 weeks, rather than 1 each week, Kubo has almost 2 years longer time frame to finish the final arc, before the anime catches up.