the problem I foresee, even if monero becomes popular is that govnts can make it illegal to sell things ie accept payment for monero. You then have the problem of advertising your products legally.  And the whole system collapses, back to the darknet where it currently is.  This is true of all crypto.  Privacy is great, but in the end to actually buy real world goods there is no privacy thats legal. Because the seller must be visible.