There is no deadline, do not get scammed
Sure, there is no deadline. However, if BIP-110 rules will expire on their Blake chain, and won't be renewed after a year, by some more restrictive soft-fork, then some transactions from BTC may be replayed on BIP-110 chain later.
But anyway: if they will keep fighting with the spam, then there should be that way or another, to relay something, which they would block. And of course, all coins, touched by newly minted blocks, will remain splitted.
a dead chain without replay protection
They introduced SIGHASH_UNIFIED, so people can use it, if they want to split their coins.
you'd have to download some software that does it for that chain
If you don't want to install Knots, then you don't have to. All that is needed, is using P2PK, 84 bytes OP_RETURN, or anything else they blocked. All transactions can be signed from Core, and once you split your coins, they will remain splitted, because the effort to unsplit them is quite huge, and require making identical coinbase transactions on both chains.
latest version of Bitcoin Knots released a month ago, which means no proper support for blake2b hard fork
Which is why using anything they blocked, and making a self-transfer, is a safer way, and works since the beginning of their fork, even before they turned into Blake:
https://bitcointalk.org/index.php?topic=5590674.msg67025339#msg67025339