HONG KONG, Aug 23 (Reuters Breakingviews) – Volkswagen’s (VOWG_p.DE) China shortcut sets a tricky roadmap for its western rivals. The $69 billion carmaker plans to invest $700 million in Xpeng (9868.HK) to gain access to the Chinese upstart’s technology, speeding up development of its own electric cars. An increasingly competitive Chinese market means others may also need to plot a new route. The idea was borne of necessity. VW’s flagship battery-powered models got off to a slow start in China, and have struggled to keep up even as Middle Kingdom consumers began to take a serious interest in electric vehicles….