The fact that this can happen on a blockchain means it is overly centralized.
We will also reduce the support for STEEM over time, reducing the number of pairs announced, and not ruling out other actions too.
The best advice I can give to Dan is to create a fork of STEEM just before the hard fork, and we will likely support that.
If a blockchain gets overly centralized, we should fork away from it.
I believe only 3 exchanges have enabled deposits/withdrawals. While the witnesses are back channeling and scheming on the next round of accounts to seize, consider this: How many times can this be done before no exchange will list STEEM?
I had a look at some of the accounts included in this fork. Everyone should look at them. @mottler has been a dormant hodler since 2016. @znnuksfe has been a curation account since 2017. If you bought an account from @blocktrades or bought SP from @blocktrades your account could be the next seized.
The one place your funds should be safe is your wallet.