Currently Lithium is safe but I would be checking on the Magnesium battery technology every few months as not to be caught out on an up trending newer technology eating into and causing a decline in lithium. That said , Lithium should be fairly safe for 3 to 5 years as the capital investment will keep the hooks into Lithium companies. It is interesting thinking of battery technology transitions, carbon to alkaline to nickel cadmium to nickel metal hydride to lithium ion to lithium polymer, have look at the transition times and as a rough measure look at future technology timeframes.
