Will kerosene reserves deplete long before oil?
No.

At the moment, we use cracking to turn heavy, long-chain hydrocarbons into more valuable short-chain hydrocarbons, such as petrol/gasoline and kerosene; as a general rule, lighter hydrocarbons are more valuable, at least up to butane.

Generally, it might take the form:

C$_{16}$H$_{34}$ $\ce{-&gt;}$ 2 C$_8$H$_{18}$  (Octane, a typical petrol component)

Note that this is not balanced; to crack to fully-saturated products we need to add hydrogen, usually made from natural gas and water. This is why you sometimes see that a refinery will take 1 tonne of heavy crude and make 1.1 tonnes of petroleum products. This is called 'refinery gain'. 

Essentially, as long as we have hydrocarbon feedstocks, we can make kerosene.