I think the
Entwives disappeared for good, being destroyed with their gardens in the
War of the Last Alliance when
Sauron pursued a scorched earth policy and burned their land against the advance of the Allies down the
Anduin. They survived only in the 'agriculture' transmitted to
Men (and
Hobbits). Some, of course, may have fled east, or even have become enslaved: tyrants even in such
tales must have an economic and agricultural background to their soldiers and metal-workers. If any survived so, they would indeed be far estranged from the
Ents, and any rapprochement would be difficult- unless experience in industrial and militarized agriculture had made them a little more anarchic. I hope so. I don't know.