This is a very exciting realm, Adrien, where my
experience is that more and more folks are interested in these savannah style,
perennial, agroforested, silvo-pastoral systems... thankfully! Marks excellent book is only increasing the awaremess and incentive of folks to try this....
The systems I've seen that use Holistic management along with keyline and savannah style tree systems are only recently being implemented, and not as far along as New Forest Farm (though as you mention, mark is not doing holistic planned grazing, per se). These are clients of mine, who have begun to implement these kinds of systems, which obviously takes time to do, and to get up and running. You can't start with a 'turn-key' system with all the
trees grown, pastures diverese and abundant, animals humming through their 'ballet in the pasture' (Salatin's term), etc...
What all of these places do have is a holistic goal, a vision of the healthy functioning landscape they wish to see there, a design, and a plan to work towards the vision in steps, monitoring and adjusting as needed, all along the way! My hat is off to them, and there are more folks like them all the time! It is a deep honor to work with folks with such vision and among my favorite kinds of designs to do...