Based on my knowledge of the situation, it is possible for others, but they put in a ton of work to do it specifically for Decred and Litecoin. I assume the method will find its way into the crypto community at some point, whether they share it or someone else figures out how to do it.
I'm not exactly sure, but I think that Bitcoin's blockchain is a bit more rigid, which is probably why they tried it with Litecoin and Decred. I'm not exactly sure whether it will end up part of Bitcoin's blockchain. It would require over half of Bitcoin users to vote in favor of changing it to add the feature, if I'm not mistaken, and a majority of Bitcoin users seem highly opposed to editing the blockchain, even if you could get over half of them to vote.