Read in an article in a Middle Eastern travel magazine where RB said that the thought of tagging on another destination onto the Dubai has not been ruled out. Muscat was suggested as a possibility. He also expressed an interest in Abu Dhabi and also eventually Doha as well.
Read somewhere else that Virgin was considering a partnership with Emirates on the Dubai route. Possibly codesharing on VS west bound routes and the reverse on some EK east bound routes. Think DXB lounge access was another feature that was mentioned.
Don't think DXB is a mistake - the city is expanding at a huge rate and is a growing holiday destination. The Virgin brand will undoubtedly prove popular.