I doubt its a harbinger of a Nasdaq listing, but I still think its a good move.  

Lots of Americans prefer to buy the US listing, even if its a Canadian based company with greater liquidity on a Canadian exchange.  Buying on a foreign exchange adds currency risk, and there may even be tax implications....although I'm not sure about that. 

The thing with CNW is that if you're on a site like Yahoo Finance, and you have RVXCF on a watchlist but not RVX.TO....then the news doesn't show up with CNW.