From the article:
Umbrella Drinks Or Ice Cream Drinks
Those fruity, creamy concoctions can make an impression. But is that an impression you want to make?
"Drinks with umbrellas and lots of garnish (cherries, oranges, pineapples) or those with contents on the rim are usually quite young," he said. "You don't catch many guys drinking anything like this; it's mostly college-aged girls."
I'm a guy who lives in a trendy apartment complex. I often take fruity, creamy, frozen concoctions to the pool - replete with garnish, umbrella and straw. They're a great conversation starter...
As for the next trendy drink... I'd like to guess frozen coffees and frozen teas because they're delicious and loaded with caffeine, booze and tasty goodness. Unfortunately, they're labor- and time-intensive so mass-market bars wouldn't be keen on the idea.
I'll go with shooters as the next trendy drink. Especially shooters with rum, fruit juice and some oddball liqueur.