Do NXT holders in exchanges also get ignis?
I don't think so.
Wouldn't it be in the interest of the exchanges to support this and prevent massive withrawal?
They can but they don't have to.
Why take chances?
Let me show you the safe way:
Today.Download and install the wallet from
https://nxt.org/downloadCreate a new account, remember/write down your passphrase, don't forget it.
Withdraw ARDR from the exchange to your address, the one that starts with NXT- (can be found in the top left corner of the wallet, also called Account id).
Sync the blockchain to the end (can take a few hours depending on your hardware speed) and you will see your ARDR under Asset exchange.
In September.Wait for Ardor platform launch in September, download the Ardor wallet when it becomes available and log in using the same passphrase.