Lauren,
Thanks for your question!
At this time Disney has not included 
Savi's Workshop on their list of shops that will be operational when the park reopens on July 15th. How quickly Disney will add more entertainment and shopping venues to the operational list by the time you visit in late August is simply not known, though it could open before you arrive. You can always check as the vacation gets closer at the 
Available Experiences page. This page shows you all the attractions, entertainment, and shops that will be open, by park.
I understand that this puts a dent in your 
Star Wars: Galaxy's Edge plans, however you may want to tell your boys about the nearby 
Droid Depot experience and see if that might be a worthy replacement. The experience is really fun, it allows for their own creativity, and the droid is a fun keepsake from the trip.
And as Leia tells Rey, 
"Never underestimate a droid". 
Have a Magical Experience!
Doug