I don't know where this conspiracy theory came from but it's patently absurd. Hong Kong already shares a river border with Shenzhen on which there are at least

I don't know where this conspiracy theory came from but it's patently absurd. Hong Kong already shares a river border with Shenzhen on which there are at least 7 ~100m long bridges as well as 1 ~3km long bridge that can put Chinese tanks directly onto HK New Territories. The HK-Zhuhai-Macau bridge is a 55km long bridge connecting a 8x smaller city in China to Lantau Island which then requires another separate two bridge crossing to reach the New Territories (and then another to reach HK Island). The military strategic value of this bridge is less than nil. The bridge was built for its stated purpose which was to increase integration and economic growth of the Greater Bay Area. The indirect effect of this is to tie HK's economy more deeply into the Mainland's so that HK becomes assimilated but there this was plainly stated from the beginning of the project.