Since the time required to develop a genetically settled, new tobacco variety is about 7 years, involving dozens to hundreds of plants each grow, the probability of a real find is fairly low.
Other than varieties laboriously and specifically created for resistance to a particular tobacco disease, most of the thousands of currently existing tobacco varieties arose due to random carelessness, prior to knowledge of the laws of genetics becoming widely known about 100 years ago.
I got seed from attempting to cross rustica and tabacum once but it did not germinate. That was for fun. I do foresee growing tobacco another twenty years, so this is something I'm interested in, but instead of interspecies, just two tobaccos, probably two tobaccos I like that are different enough to warrant it.
The reason Bob says it takes so long is because tobacco is tetraploid so the genetics are really complicated in regards to which sequences get expressed and which do not. I'm patient enough to try and I doubt two tobaccos I like will turn into something I dislike.
So from last year's crop, I'm really impressed with Simox as a sun cured tobacco. Maybe I'll try mixing it with Goose Creek this year.