This is actually a pretty sophisticated picture, not as easy as one would perceive superficially.
1) In-land China is still a vast region with very cheap labor, while the labor becomes costly in the coastal areas. Though transport expenses would cancel part of the in-land labor benefit, there is still a price gap allowing manufacturers move to inland. In addition, inland Chinese are also pretty well educated. Infrastructure is impressive, too. Chongqing is a typical example where, if I remember WSJs claim correctly, last year export from the in-land mega city increased by 161% YOY!
2) It is only natural evolution for low end industries to fade away in China. The question is where will those industries move into? One cant assume they will automatically go to low cost countries: there are abundant countries with much lower labor cost than that in China, yet the industries failed to go there but to China. Stable social environment, business friendly bureaucracy, educated labors, reasonably good infrastructure, etc, all these counts. This how makes some Indian arguments laughable when they gleefully taunt cheap labor China: India is worse than cheap labor China though India has even cheaper labor, because India lacks business friendly bureaucracy, misses well-educated labors, doesnt possess sound infrastructure, etc. It is therefore imperative for those candidate countries to invest in education and infrastructure, etc.
Sun-set industries, such as shoes, toys, clothes etc will inevitably decrease in volume in China. Some of them will go upgrade, some will move out. Im not sure about shoes or toys, but I am a little bit more familiar with garment industry, as my remote cousin is in the business. This industry has already moved many manufacturing plants to Cambodia, Bangladesh, etc. Remaining factories are moving to higher quality garments, for instance taking complex customer order with sophisticated design, high quality materials and by using standardized laboratories for testing colors, dyes, rayon, etc.