Jan Kucera wrote:

. . . 

I would like to make an appeal to everyone who feels like they have significant notes, drafts, or work-to-come they have spent decades on, if you don’t want these to suddenly disappear, please make provisions for someone to be able to pick it up or turn into a treasure to be found by future generations.

 
Perhaps one part of this might be for members to identify the significant unpublished material of others to preserve.

For example: 
Part 2 Verba Indoarica.
This was posted on the Indology list in 2019 by Asko Parpola:
A little earlier, 14 Nov 2017, he had written me: "For the time being I am concentrating on the second volume of my VIA [Verba Indo-Arica] (II: Radices secundariae) for which I’ll be looking for a fine printer in the second half of next year.” Although the first volume, I: Radices primariae (1997, 600 pp.), was printed by the publishing house of the Viennese Academy of Sciences, it was not included in any publication series (apparently the author was too shy to ask), and Werba had to pay the printing himself.  It is to be hoped that his Viennese colleagues now have the second volume duly published in an appropriate series.

Part 2 Avesta Grammar in comparison with Sanskrit by A. V. Williams Jackson
I vaguely recall being told or reading somewhere that the manuscript for this unpublished part 2  is sitting in a university archive somewhere (Columbia?)

Thanks,
Harry Spier