The MU and SNDK dilemma - cheap or overvalued?

From Bloomberg today "Soaring profits have helped keep memory chipmakers’ stock market valuations in check despite the rally. Indeed, Micron and Sandisk look downright cheap at around 10 times earnings over next 12 months, compared with the Philadelphia semiconductor index, which trades at almost 27 times. However, those valuations are based on the assumption that this boom is going to last. Using trailing profits, valuations look much more extreme, with Micron trading at a multiple of 46 and Sandisk at 58. The semiconductor index is around 71 times profits, the most expensive since the aftermath of the 2008 financial crisis. And at 15 times sales, it’s at the highest in data going back to 2002 and more than three times the average over that span"