I'd like to see the removal, or at least a modification of the private trade system. The way I see it is, it would still be possible to trade with persons, simply post your trade in the trade tab, notify the other person that the trade is up, and decline all requests other than the other party you wish to trade with.
As it is, the private trade system is abused by some players, and it doesn't seem to offer any real advantage over open trade. I believe it would also serve to prevent some "pushing", or multi-accounting, by showing what trades are up to everyone. Just my two cents, take it or leave it.

