Altria investors are very excited by the prospects for NJOY, but the tobacco company is nowhere near replacing its core business.The stock of Altria (MO -1.07%) has risen more than 20% over the past year as investor sentiment around cigarette makers has improved across the board. The big story for all the major companies in the space has been the growth of cigarette alternatives, like vaping products and pouches.For Altria, after a failed investment in Juul, the hot story is its purchase of NJOY. But don't ...