That's probably one of the things that saved Shanny's bacon for this season. Pelley may be a financial whiz but he isn't from the NHL so immediately taking the nuclear option was never likely to happen. He needs to learn the lay of the land so to speak, including possible replacement options. All he knows coming in is that the organization is a wrecking ball in the regular season and they make tons of money. Plus whatever the board decided to fill him in on, keeping in mind Shanahan is their creature so they aren't going to lead with " he's incompetent but his excuses sound so believable".
I think Tre and BS both have to make big things happen this year. Treliving is Shanny's hire so they might be riding the same rail out of town. The new guy being an outside resets the clock but only for a year.