I'm against of forced discount of already emitted coins because this destroys trust to development team. Voluntary donations is the only fair way to do this.
I'm in favor of the 21 curve. I suggest this be done by leaving the formula along and changing the block target back to two minutes. The original premise for one minute was to help solo mining. Solo mining is already difficult and new miners are complaining that they often don't get anything, and the coin is only a week old! The increased orphans created by one minute blocks are not a worthwhile trade off.
Probably the first purpose of collected "excess" coins would be pool development?