I am not sure there will be any lawsuit (yet).
The reason given for the resignations was that the chair had been asked to resign, refused, and threatened to sue the charity.
So they resigned en masse rather than have the charity foot the bill for a costly court case. Whether the patrons should have stepped in themselves is a moot point. There may be very valid legal reasons for this being unwise.
It is all very rum. Personally, I did not particularly like parts of the chair's statement. It seemed to contain some of the same sort of thinly veiled incendiary accusations, coupled with a slightly holier than thou tone, that many of us , including me, have long criticised the Sussexes for. I will be very happy to be proved wrong!
The CC report will be fascinating.
Meanwhile they can bid farewell to the polo funding, and if they has USAID money too that is obviously gone now also.
I suspect the charity will shortly find it is up the polluted watercourse without the requisite propulsion device.