No, they can't sell it unless someone wants to buy it. Miners will either go out of business or get into the business until the difficulty level approaches whatever a marginal profit is above whatever the current price of BTC is
If you’re living with a 2015 13” Pro the MacBook Air is a huge upgrade if you opt for 16 RAM and the quad core CPU. I just upgraded and it can handle anything I throw at it (.NET Core, Angular, Docker, JetBrains IDEs)