Young college graduates may be moving out of vibrant metros such as Beijing, Shanghai and Guangzhou, to reside in smaller cities, but rents there are not altogether friendly either.

These youngsters, dubbed the "ant tribe", have been pushed to the sidelines in cities. Since they can hardly afford to rent an apartment in big cities where living costs are higher, they cluster together in villages on the fringes of urban centers.

This generation, born after 1980, has been expanding rapidly into cities ever since China massively increased its university enrollment program starting 2003. A further 6.3 million graduates are expected to join migrant workers and other job hunters this year.

To cater to this growing tribe, the government has rolled out public rental schemes nationwide aimed at renters in the mid-to-low income bracket. It's a sensible move.

Yet, whether the scheme will be implemented in full is the question. For one, who will build these low-income houses?

The government says it wants the public rental scheme to evolve via a market-based mechanism, with real estate firms taking the lead instead of local authorities. But it is difficult to envisage how profit-driven developers can be persuaded to participate without abundant government incentives.

Every year since 2004, housing prices nationwide have climbed apace with China's growing economy. Prices have risen for a longer period, and more rapidly, in major metropolises such as Beijing and Shanghai. Now, it is being repeated across smaller cities.

If the question of "ant tribe" clusters, which are no more than urban shantytowns, is to be addressed in the long term, affordable housing holds the key.