The View From Seven blog has a pretty good rundown of the likeliest new routes in and out of Winnipeg:
http://theviewfromseven.wordpress.co...al-new-routes/
For the foreseeable future, Canada is going to continue to have one major international gateway (Toronto) along with three lesser gateways (Vancouver, Calgary, Montreal). There is little chance of Winnipeg joining those ranks anytime soon.
The most likely path to improving WJARIA is in bolstering the number of domestic and transborder destinations - Edmonton, Ottawa and Halifax are good examples of second-tier airports that offer a wide range of destinations in North America, and provide us with good models to follow. Having direct access to a couple of additional US hubs (for example, Newark, Atlanta or San Francisco) would probably make more of a difference in the long run than would 5x a week service direct to London.