Strange simulus idea

There is a very strange article in the New York Times. Make the Tax Cuts Work is by Len Burman, director of the Urban-Brookings Tax Policy Center. In his article Burman says,

But if they were repealed in a year, the Bush tax cuts could spur a burst of economic activity in 2008. If people knew that their tax rates were going up next year, they’d work to make sure that more of their income is taxed at this year’s lower rates. Investors would likewise have a giant incentive to cash out their capital gains now to avoid paying higher taxes later.

But if this is right then why doesn't the government declare that as from next year the tax rate will be 100% and then people would work like crazy this year to avoid having their income taxed at 100% next year. The increase in work this year would be huge!

The problem here seems to be short term thinking. Maybe people would work harder today, but how much extra spending would result? It seems likely that people would spend their addition income over time, not all today. So any increase in consumption today would be small which means the stimulus resulting form this spending would be small. And what of the future? Would work effort in the future be reduced under Burman's plan? So future spending and stimulus would be reduced. So in the future some additional stimulus plan would be needed, which I'm sure Mr Burman would provide.