By Patrick Johnston SINGAPORE, May 23 (Reuters) - Free-to-air TV coverage is essential if Super Rugby wants to build its profile in Asia sufficiently for the continent to host a team over the next five to 10 years, the head of the ARFU has told Reuters. With Super Rugby set to expand from 15 to 18 teams in 2016, an Asian franchise was tipped to join Argentina and a sixth team from South Africa in the competition, which also features five Australian and five New Zealand sides. Asian Rugby Union president Trevor Gregory thinks this is unrealistic while even the biggest stars of southern hemisphere rugby, such as All Blacks captain Richie McCaw, are virtually unknown in most of Asia. Gregory, who also serves as chairman of the Hong Kong Rugby Union, believes that 2021 might be a better target date for an Asian team to join the SANZAR competition and truly reap the benefits. More...