Your point about going to a consumption based model is a good one.
As for the growth rate, that's more of a short term thing in my view. Yes, it's decreased from where it was. That's because economic growth always slows as economies mature.
There are two main drivers of economic growth: productivity improvements and growth of factor inputs. The second one is considerably easier. There are remote, off-the-grid villages somewhere? Great, build a road and lay some cable and presto -- you've increased your factors as you've now brought labor online and an additional consumer market. Population growth is an increase in factor inputs (which is why immigration = growth). Women in the workforce is an increase in factor inputs.
Nascent economies have many opportunities to increase their factors, and thus they do. That's why their growth rates can look so eye-poppingly high. The Soviet Union did just that: in the 1920s, the Soviet economy grew quickly because it repurposed an almost feudal environment in the countryside to factor workers. After that, the Soviet economy stagnated because, unable to increase factors any further (especially with 10M dead in WWII or however many, plus millions less Ukranians from starvation and however many political prisoners etc), it would have to rely on productivity improvements and the Soviets were not so good at that (and they got worse over time).
China had a lot of factors to bring online, given its enormous population and the economic mess that the Cultural Revolution left. As the low-picking fruit gets harvested, the growth rate will necessarily decline. Eventually, the Chinese growth rate will, like the US growth rate, depend mostly on productivity improvements, such as those achieved through automation. Thus will China's and America's growth rates converge, unless one or the other countries pulls decisively ahead in technology.