Jimmy-
If the things that no longer exist are old enough, then any existing photographs will be public domain. For things that are more recent, illustrations provide an excellent alternative.
Not really. Do you want to substitute the photo of Mother Teresa with Charles Keating with an "illustration", a drawing? Not only would that be extremely silly, it would probably be seen as a derivative work and therefore still copyrighted. And it would give the upper hand to those who want to get rid of this image, and other images like it, for political reasons, give them yet another instrument of censorship.
Jimbo, Jimbo, Jimbo. When did the GNU bug bite you and turn you into a zealot? We should subject each fair use image to an examination process in which we seek to determine whether we can obtain an image by other means. If that is so, we should try everything -- request permission, create our own image etc. -- and leave the article without an image in the meantime. This examination should be a group process like votes for deletion. For example, I could upload an image and provide contact information, and someone else would try to request permission from that person.
If everything else fails, however, it would be extraordinarily stupid not to make use of the exemptions which copyright law explictly grants us (and to those who keep claiming that no equivalent law exists in other countries -- that's simply not true, most copyright laws have exemptions for scientific and educational use, e.g. Sec. 51 of the German copyright code). It would be a slap in the face of those who have been lobbying for broader fair use provisions.
This process is without alternative. Anything else *will* split this community.
Regards,
Erik