My trust is dated December 23, 2015 and the way I read it, it WILL apply to future NFA purchases:
How will this affect my existing gun trust?
The construction of the final rule does not apply directly to existing trusts or entities in possession of NFA weapons, but to future applications made by both individuals and entities. After July 13, 2016, you will be required to submit or do the following with any Form 1 or Form 4 application:
a complete copy of your trust and any schedule or exhibit referenced by it;
for each RP -
Two FD-258 fingerprint cards
A 2X2-inch photograph taken within the last year
A completed NFA Responsible Person Questionnaire (ATF Form 5320.23). This form will require the input of a RP's full name, position, Social Security number (optional), home address, date and place of birth and nationality
Provide CLEO "notification"
Prior to submission, the applicant must forward a completed copy of the application form (Form 1 or Form 4) and all other RPs must forward a completed copy of their Form 5320.23 to the CLEO of the locality in which the applicant or RP is located. The new rule also defines who may be considered the CLEO as "the local chief of police, county sheriff, head of the State police, or State or local district attorney or prosecutor."
Existing trusts are grandfathered in, but future Form 4 submissions are not. So, if your trust is already established, and you never add any more NFA stuff, you are grandfathered in, and notice, it does say you must submit a complete copy of your trust (not trust certification).
The entire article is here:
http://www.nfafa.org/atf41p.cfm