I think the idea of the world "running out" is bogus. I am pushing 50 and I have heard we were a decade or two away from running out as long as I can remember.If we do in fact run out of oil in ~ 50 years the world is not going to be a fun place to be and that's putting it mildly.
I think what we will see is an increase in gas prices if, or when, supplies start to run low. Every time gas prices shoot up, there is a ton of talk about alternate fuel sources. Bio Diesel was all the rage 15 years ago. Hybrids got popular during a fuel cost spike. As oil supplies run low, prices will go up, and the economics will make alternate fuel sources more attractive. I don't believe gas will ever go away, it will just get uneconomical. I bet you will be able to fill up 100 years from now.
The hybrid and electric owners I know are way more interested in cost savings on fuel rather than the benefits to the environment. In the future, I think things will depend on costs as much, if not more, than environmental concern.