The lack of upward mobility really sucks, but its not like any of the big non-O&G companies or government are a bastion of high compensation or upward mobility right now. The "Big Oil" companies (except for CNRL) are still the best, highest quality employment in this city right now if you can get in (or back in)
This is coming from someone that was out of the industry in 2015 and moved to a non-O&G company, and recently went back to O&G last year. I know a few other former colleagues who tried leaving O&G to a variety of other big Calgary companies (City, WestJet, Shaw, ATB, etc) in 2015-16, but ended up going back to "Big Oil" last year.
The great crew change isn't coming anytime soon and the best quality employment is outside of Alberta.