i suppose they will announce ahead before shutting down.
They would do that if they are solvent at that point, but what if they are insolvent or they suffer a major hack and lose most of their customers' funds, they would simply halt deposits and withdrawals, declare bankruptcy and shut down, and as usual it would now result in a long process to see if some customers can get some of their money back. So in other words, don't rely on a centralized exchange to give you an update before they shut down.
Will it affect you in any way if Binance completely shuts down ? I know there will be lot of devastating affects on crypto market of this incidence like bitcoin price will fall very sharply. Many users will also loose funds and some will loose faith on crypto.
I don't store my funds in any centralized exchange. If Binance bites the dust, so many shitcoins would be removed from the market and BTC price would temporarily drop. But at least so many people would learn that they should only hold their funds in self custody and that funds cannot be #safu in any centralized exchange.