No it will not cost Sherman his job; if this were Matt Duchene maybe you might have a point but its not, its Ryan O'Reilly. For how much we love him, hes still just Ryan O'Reilly, a 3C with potential to become a solid 2C. The Avs have to either wait for the homerun offer in order to trade him, or let him rot back in Ontario missing out on playing NHL hockey.
Also, your "bad deal" of MDZ + a high end prospect was likely already rejected by Sather, I recall an article that stated Sather turned it down. Also, Sather probably wants no part of O'Reilly because he'll just try to give him a bridge deal, its the way Sather is with RFA's.
Personally I hope O'Reilly rots back home for as long as possible before finally giving in. Signs the deal, comes to practice and on the first day, scraps with Duchene. Second day, scraps with Landeskog. Third day, Scraps with Bordeleau. Then he'll have earned the respect of the locker-room lol..... Maybe on 1st game ask him to scrap the opposition's heavyweight too