Eight states have repealed the rule against perpetuities.
These states are Alaska (repealed the rule for vesting of
property interests), Delaware (repealed entirely for
personal property interest held in trust; 110 year rule for
real property held directly in trust), Idaho, Kentucky
(repealing the rule interests in real or personal property),
New Jersey, Pennsylvania, Rhode Island, South Dakota.
Nine states have adopted longer fixed periods for the rule
against perpetuities, sometimes only for certain types of
property. These states are Alabama (100 years for property
not in trust; 360 years for property in trust), Arizona (500
years), Colorado (1,000 years), Delaware (110 years for real
property held in trust); Florida (360 years), Nevada (365
years), Tennessee (360 years), Utah (1,000 years),
Washington (150 years).
Source: http://www.actec.org/assets/1/6/Zaritsky_RAP_Survey.pdf
In those states--even the ones with the absent or absurdly long vesting period limitations--there may be other rules that make it hostile for multi-generational trusts. But I'm pretty sure that in at least a few of them you can do exactly that. But I don't know enough about estate law to be able to point them out without further research. Much like the laws leveraged by lawyers and accountants who help the rich move their money off-shore, they don't generally discuss this stuff in public forums. But it's not nearly as secret or esoteric, so with some effort it should be easy to figure out which states are attracting the most business, so to speak.
Which reminds me: there are of course plenty of foreign jurisdictions that allow you to create multi-generational trusts (or trust-like devices) without any problem.
If you were establishing a multi-generational trust you'd want to put it in a politically, economically, and legally stable jurisdiction. Historically those options were limited to the U.S., U.K., and maybe a couple of other European nations. That's less the case now. But who knows what the world will look like in a 100 years. There's plenty of reason to want to keep money in the U.S. So I wouldn't argue that U.S. law is inconsequential in the face of foreign options. I just don't see us returning to an earlier time wrt restraints on generational wealth transfers. The viability of foreign options makes it even more difficult to reverse the trend.