the bizjet crowd will simply decamp to friendlier shores and keep on flying.
I think that is true. So this will affect only the small fry. Same as the 2005 DfT proposal to boot out N-regs after 90 days; there were relatively easy work-arounds for internationally moving jet fleet operators.
However, there is zero doubt that the trustee is the legal owner, and piercing a trust arrangement is very difficult. Trusts have been established for centuries and are accepted widely.
There is a summary of the present EASA proposals on the pplir.org site, which presents a rather less certain certainty of outcome than has been written here (because all but one of the EASA proposals have some way to go before becoming law, and the one which is law is too vague to mean much) but you have to be a member to read it...