Good thing you chose these exchanges but never say you're safe 100%, you will never know what is their plan.
I've been a user of Bittrex but stopped before the collapse of this site. I have no bad experience with Bittrex nor do I think this would happen to them but yes, it was hard to figure out what is their mind (owners), they can stop their operations if they want to and show different stories to the public about their closure. Even in Kucoin, we can't assure our funds are safe until it was totally deposited in our fully controlled wallet address.