They don't care when your trust/corp was formed. Once the rule change happens legal entity transfers will all be treated the same whether your company is 20 years old or a brand new trust.
The big question is whether they'll kick all the stuff already in the pipeline back out or let them go through.
And whether they feel politically/judicially invincible enough to retroactively apply the rule and invalidate all tax stamps issued to entities under the current rules.
Talking to a NFA clerk last week about this; the term "fiasco" came up several times. They said that they expect this to be a complete nightmare, as the folks who have Decreed From On High That This Will Be So have never, ever talked to anyone who actually works or deals with NFA items (on the government side, even) and could not in any way care less about any Americans.
This is one piece of the ongoing punishment for "gunnies" because they did not back The One. And that was what the NFA clerk said...just their opinion, of course, but it was very amusing hearing what sounds like this (and other) board's usual echo chamber of complaints coming from that side of the discussion.