Yeah the total tea market (and cheap bubble milk tea) is $9.5billion USD which is still ten times larger than its coffee market. Starbucks is not going anywhere, but I do think the growth will slow; much like in other world cities that are already over-saturated with Starbucks, some Chinese urbanites are already evolving towards more intimate local cafes. Quote from that article:

• "I like quieter venues and so usually go to rather arty, yuppie places,” she said, while sipping a brew at downtown Mellower Coffee, which has coffees with names like “sweet little rain” - an Americano with a “cloud” of candyfloss."