Just because the CEO was arrested, doesn't mean that Telegram is shut down, as you can see at the moment it still continues to function at a normal rate without a problem. Hell even Binance got rid of CZ and still functions properly, I am sure they still consult him but he is no longer the CEO, while he is not jailed, they had to pay insane amount as a fine, and they had to fire him as their CEO for it. So Telegram itself will be fine, who should be worried is the CEO, no idea if he can get out of this or not, but the fact that he went to a nation where he was arrested shows that he had some confidence he can beat the case.