Most Chinese words now part of English show, in their spelling and meaning, to have been borrowed a long time ago, often from non-Mandarin Chinese varieties like Cantonese. Kowtow, gung ho and to shanghai are now impeccably English words we use with no reference to China itself. Kung fu, tai chi, feng shui and the like are Chinese concepts and practices westerners are aware of. And of course bok choy, chow mein and others are merely Chinese foods that westerners eat; I would say we borrowed the foods, and their Chinese names merely hitched a ride into English.
Given China's rocket-ride to prominence, why so little borrowing? We import words from other languages that are hard for English-speakers to pronounce. We borrow from languages with other writing systems (Yiddish, Russian, Arabic). We borrow from culturally distant places (India, Japan). We borrow verbs (kowtow) and nouns (tsunami) and exclamations (banzai!, oy!). We borrow concrete things (sushi) and abstract ones (Schadenfreude, ennui). We borrow not only from friends, but from rivals and enemies (flak from German in the second world war, samizdat from Russian during the cold war, too many words to count from French during the long Anglo-French rivalry).
So perhaps China's rise is simply too new, and we just need another 20 years or so. We've seen a similar film before. Japan's sudden opening to the world, a world war, and then forty years of an economic boom put quite a few Japanese words and concepts into the Anglophone mind: kamikaze, futon, haiku, kabuki, origami, karaoke, tycoon, tsunami, jiu-jitsu, zen and honcho are all common English words that nowadays can be used without any reference to Japan. Add to that the more specifically Japanese phenomena well known to the English-speaking world: karate, judo, sumo, bonsai, manga, pachinko, samurai, shogun, noh and kimono, say, not to mention foods from the bland (tofu) to the potentially fatal (fugu). Of course, Japanese borrowed some of these words from Chinese, like zen (modern Mandarin chán) and tofu (dòufu). But English borrowed them from Japanese, not Chinese.
It seems likely English will borrow from Chinese, too, as trade, cultural and personal connections between China and the west grow. And perhaps there's an elusive "cool" element, a cultural cachet in the West that China has yet to attain. If China gets there one day, this would certainly boost China's linguistic exports. Whether future Chinese borrowings will be new edibles, cultural items or even philosophical terms will depend on China's development and how the West responds. In other words, we should hope Chinese terms we will adopt will be more of the guanxi than of the flak variety.