The Guangzhou Daily has reported that there's no such plan. In a press conference yesterday, it seems, a spokesman refuted rumours that had been "hyped up" by the foreign media: "Guo Yuewen, spokesman for the provincial Party committee, in response to the claims, responded in a sonorous and forceful manner: 'There is no such thing!'"
In a numbingly dense example of the kind of jargon that Chinese Communist planners revel in, he then explained that...
"in order to fully implement the "Pearl River Delta Region Reform & Development Programme Outline (2008-2020)" authorized by the State Council, Guangdong province is now working hard at setting about a “Five Unifications Programme” for the Pearl River Delta, consisting of basic facility construction, industrial layout, urban-rural planning, environmental protection and basic public services, actively promoting the construction of the three economic circles of Guangzhou, Foshan and Zhaoqing; Shenzhen, Dongguan and Huizhou; and Zhuhai, Zhongshan and Jiangmen, to promote more rapidly the Pearl River Delta’s economic and social development mainly from an economic level, with the aim of, following governmental impetus, market leadership and the principle of mutual benefit, perfectly coordinating linked mechanisms, optimizing the allocation of resources and establishing a system of overall urban planning coordination with foundational facilities that are both mutually constructed and benefited from, industrial development that is cooperative and of a win-win nature, and a unified development layout of collaborative management of public affairs, to strengthen the Pearl River Delta cities' integral core competitiveness. Guo Yuewen ended by reiterating that the provincial Party committee and the provincial government had absolutely no intention whatsoever to unify the nine cities of the Pearl River Delta!"
To be honest, I got tired of trying to relate one clause to another halfway through that paragraph, so my apologies if the translation has some of that catchy economics-speak in the wrong order. The sense is clear: they're unifying the cities of the Pearl River Delta on some level or other, but not, repeat not, creating the world's biggest megacity. Or something.