Last I heard about them (~2 years ago) most of the devs left and many projects migrated away from counterparty. Looks like they are still alive and also were in the works for some major updates. Might be worth a shot I guess.
OP if you want to have a look or ask around this is their thread https://bitcointalksearch.org/topic/annxcp-counterparty-pioneering-peer-to-peer-finance-official-thread-395761
That's indeed an issue. Many efforts in the semi-professional blockchain field are left as quickly as they are started. But I was talking about the counterparty protocol, not the organization. It is still technically suitable for implementing NFT. It was even featured in the book "Mastering Bitcoin" from O'Reilly because it can serve as a key example of what is technically possible on the Bitcoin blockchain. And even with the original counterparty developers didn't continue their work, what was written to the blockchain is still immutable and can be continued upon.
It will all depend on the value of the artwork whether it makes sense to go through the effort of making it work on the Bitcoin blockchain by finding developers who can make it work using the protocols that are already there, or whether to go with one of the shiny new blockchains. Ethereum still doing severe changes like moving from PoW to PoS can serve as an indication that its long-term viability still has to be decided, though.