Is ibm.nyse.com, dec.nyse, mci.nasdaq.com a problem? This takes the
arbitrary decision out of accepting or denying someone access to the
.com hierarchy and enforces and already strict naming.
US citizens would have to remember country codes for Germany to get
Seimens, Holland to get Phillips, etc. Not a terrible side effect.
Some US citizens may even come to startling revelations like that
Denmark, Hollans, Norway, and Sweeden are separate countries. 
For
US companies everyone would need to know the exchange and trading
symbol for US companies or what state the company was in if privately
held. For most big US corporations nyse.com is a good bet, although
some of the trading symbols are less cute than what we see in .com.
There are too many proposals already, but having a non-arbitrary means
of denying access to a small set of top levels (nyse.com, amex.com,
nasdac.com) is a handy feature.
Curtis