I didn't look up the tar sands because it is kind of irrelevant considering the green river formation in the US alone has 3 trillion barrels worth of shale oil with half expected to be recoverable [0] and that is being extracted at current prices so no need for prices to go up. At 100 million barrels of oil usage per day for the globe, it could support the world's oil usage by itself for over 40 years. The US consumes about a fifth of global oil so that's 200 years worth of oil for you. There are also other shale oil sources in the US.
2.) shale oil is NOT being extracted - you're confusing with tight oil
3.) we don't know whether extracting shale oil even makes sense - for all we know, it might never become economically and energetically viable
(IMHO, considering global warming, tight oil/gas & tar sands did not make sense in the first place either - especially since the whole tight oil industry hasn't even shown to be financially and therefore probably energetically profitable !)
4.) even if we did, the (E)ROI (and therefore, the pollution involved) is likely to be dismal
5.) a century ago, world oil production was a few million barrels per day, you can't just both assume business as usual and the consumption to stay flat when taking into account future consumption...
[0]: https://en.wikipedia.org/wiki/Green_River_Formation#Oil_shal...