Some other cities other than the ones located in Quebec could be bilingual too. I believe it is mostly dependent on the job itself, rather than the location of the job. I used to work for a Montreal company which had branches in different cities and my position in Ottawa was in "English". If you do a research to find your job in Canada without city restriction, you will have the idea what percentage of the posted jobs are demanding bilingualism and what percentage are in one language only. Another example is Government jobs: 80% of Government jobs need bilingualism.
In brief: If you don't know French, you will loose 20-30% of job opportunities in private sector and 80% of opportunities in Government jobs.
But don't worry, many people don't know even one French word (including me) and find their job and are happy!