City Council could, but then again that is what was threatened the last time a city income tax was on the ballot, and it never happened. Three City Council members are up for re-election in 2012. If they do cut police and fire protection, you have the power to send them packing in November. Remind them.
The idea of cutting police and fire services is a cheap trick to scare people into handing over their wallets. There are alternatives to controlling costs, as described elsewhere in this FAQ.