A recent post by @ned gave SOME insight, but still a lack of firm or even estimated timeline alternative to the originally estimated timeline of Q2 2018:
There were a lot of positives in that article, them pointing to specific GitHub Stories regarding Core Functionality for SMTs. They also point out that they are working around the clock to get the TestNet up and running for SMTs, but I'm still hoping for a more firm commitment to a timeline if at all possible. If not possible, I would love to see them be upfront about that, as I think honesty and transparency are HUGELY valued, ESPECIALLY by Blockchain Enthusiasists and people in this space in general! They point out:
We will continue to keep you up to date on our progress and will let you know as soon as the Forerunner testnet is ready for use."
and I recommend you check out the specific issues/stories in GitHub that they are working on/have finished by navigating to the article mentioned above. Links to the GitHub Stories can be found there and the stories range from the ability to implement SMTs to the way they are tracked, transferred, voted with, etc. I truly do believe they're making good progress and headed toward SMTs. I think that we will see them this year, but I hope it is within Q3 at the latest, with my extremely optimistic side thinking it could occur within the next 2 months (the testnet, that is). I'm excited for the future of Steem, with the implementation of SMTs being a huge part of that excitement, followed by the many different expressions of the current Steem Blockchain being a close second, such as DApps like DTube and DLive. Steem on and get ready for SMTs in the near future!