Look at what Boston did last year. And this year they are in a playoff position (so far), they've done that all the time in recent history.
I would rate to lose OEL, McCabe, McMann, but in the end, if the price is good, why the hell not ? I would also try to move Rielly and keep McCabe and OEL.
And if the Leafs don't qualify for Playoffs this year and end up being luck enough to get a lottery win, along with decent picks and prospect this can be done and team should be back in content territory next year.
I have absolute no faith in our GM to do so. He will probably stand pat.