EXACTLY. No need to lose a lot of sleep over running out of oil...there are plenty of alternatives that are more expensive than oil today, but could easily be economically viable if oil prices rise further. Once these technologies get a foothold in the market, economy of scale will drive their cost down further.

Unfortunately, there are no alternative fuels for airliners...the problem is not engines...turbine engines will run on anything that burns (liquid or solid). The M1 Abrahms tank (which has a turboshaft main engine) was once run on peanut butter as a demonstration. The problem for airplanes is fuel handling and storage...kerosene is VERY stable, and has very good specific energy and specific volume compared to any alternative. The only practical alternative is artificial kerosene, which is technically feasible but expensive. Hopefully it will get cheaper (the military is doing research, they need kerosene too). Liquid Hydrogen is about as corrosive as battery acid. It's so dangerous that nasa was afraid to use it for the big Apollo stages...they chose kerosene instead. Hydrogen has been used on dirigibles and the space shuttle however

Less-energetic alternatives (like natural gas) would provide a drastic range reduction...you'd need a 747 with full tanks to do DEN-LAX.