Going back to the 5% inactivity fee, where dividends would more than compensate for this.
This may become a problem if people loose their bitshares (lost passphrase, hard drive etc). In such a situation, their address will continue to collect dividends, which will accumulate, collecting more dividends. This will create a blackhole for BitShares.
Stretch this out over a long period of time and BitShares will disappear into this black holes! Perhaps this will take very long and is nothing to worry about, but it is still a potential problem.
Maybe after 5 years of inactivity dividends stops being paid to those BTS. Then inactivity fees will recirculate the BTS back into the ecosystem.