But that's what I'm saying. If the need for the oil decreased, the need for that type of investment would also decrease, freeing up that $$$ for other things. While there would be an additional expenditure up front, the ROI would be a lot more than just $$$ as it is now.
I think that everyone tries to make the solution too complicated. If we always let ourselves get mired in the details of what might happen, hardly anything would ever get done, which seems to be the way things are going at the moment.
And noone said anything about pushing all current non-green vehicles into a landfill. Subsidizing hybrids would just be a way to make them more affordable so that more people could own them, causing the by-product of being able to drive them, even if it was only every other day for those of us who like to have a second, cool-factor vehicle in the garage too (like say a VX) because of it's uniqueness.
Those trillions may be considered an investment by some, but it could be debated whether that is an investment in the future.