Microsoft will end support for Windows Phone 8 in July 2014, just 18 months after the start of the support lifecycle. The short period suggests the mobile OS is not being targeted heavily at enterprises, which have longer upgrade cycles, and could also cause problems for carriers focused on two-year contracts and updates. That has inevitably sparked speculation that the Windows giant is losing interest in Windows Phone and will seek to bring Windows RT to all devices. Loss of interest and investment in the mobile OS is an outcome which Nokia recently included in a list of risks, in a regulatory filing. According to Computerworld, Microsoft’s support for WP8 will end on July 8 2014, and for WP7.8, the…