I've been digging on this one for about a month, obviously all my research was fruitless. I'm never without anyway, so its not really an issue. Classic case of "if it aint broke, dont fix it". Cheers.
Tobacco is not the only plant that contains nicotine so it is very possible there is a plant undiscovered in an Asia (where cannabis originates.) that contains THC. I think that if it is discovered it will contain a marginal amount because through selective breeding we got cannabis to contain the levels it does today. Also unfortunately, it would be covered under the CSA and would be outlawed by the US, and other nations.