diff --git a/doc/design-paper/challenges.tex b/doc/design-paper/challenges.tex
index ac4845312f..62f9aee7c9 100644
--- a/doc/design-paper/challenges.tex
+++ b/doc/design-paper/challenges.tex
@@ -90,6 +90,15 @@ snipe them? Takedowns and efnet abuse and wikipedia complaints and irc
 networks. Should we allow revocation of anonymity if a threshold of
 servers want to?
 
+Image: substantial non-infringing uses. Image is a security parameter,
+since it impacts user base and perceived sustainability.
+
+Sustainability. Previous attempts have been commercial which we think
+adds a lot of unnecessary complexity and accountability. Freedom didn't
+collect enough money to pay its servers; JAP bandwidth is supported by
+continued money, and they periodically ask what they will do when it
+dries up.
+
 Logging. Making logs not revealing. A happy coincidence that verbose
 logging is our #2 performance bottleneck. Is there a way to detect
 modified servers, or to have them volunteer the information that they're