Here's a bunch of happy people listening to Disneyland's mariachis in front of one of the Frontierland eateries (Casa de Fritos?). This is a wonderful example of the entertainment that you could find all over the park in the old days (I've never cared for the ultra cute non-word "streetmosphere"). There's something so warm and happy about mariachis, with it's Mexican and "old California" heritage, it seems to be a perfect fit in Frontierland (back when Davy Crockett and Zorro were still fresh in the minds of visitors). Check out the Keppy Kaps, I've got to get me one of the yellow ones someday!
Of course there are still some street entertainers, in New Orleans Square and on Main Street. I hope they never go away!