Great letter. It reminds me of an essay written by Alan Fuerbacher. Alan F was the first to get me thinking that the prophecies about the sign and the parousia, etc, would unfold differently than what I had been taught as a JW.
As it happens, the WTS seems to be gradually shifting everything to a later fulfillment anyway. For instance, now the FDS will not be appointed over all the belongings of Christ until later, rather than since 1918.
It would not surprise me at all that one day their teaching will match your letter almost exactly.