Fox won't necessarily do anything to CBC. Fox, as currently configured, is incessantly America-oriented. Foreign news is, well, foreign. And if Fox loads up on Canadian news, it may alienate American viewers. If Fox doesn't change, they will bore Canadians to changing the channel. If they do change, they risk losing the home audience.
The result would be to give Canadians an opportunity to see a different perspective on the US and a different geopolitical persective.
Mother Corp would have to start rebalancing its geopolitical perspectives because there would then be a reality check which the competing Canadian networks and the existing left biased US networks do not sufficiantly provide.