I would love it if you could post it on Psi-k !!!
It's true that Leopold did it once, but as you already noted in your question, even you didn't see it, which means a lot of other people didn't either. I'm on Psi-k and a few other related mailing lists but get so many emails that I am really not able to open them all these days. The administrators will also not mind if you post this site again: I think we should do it every few months or so, and it's already been 3 months (an entire season!) since Leopold posted there.
As for whether or not MMSE is going to stay: Tyberius's comment gives a lot of insights about this. The truth is that we never know, because SE company can always change their mind about things and get rid of sites that they unilaterally feel are not worth keeping. But if you can help us to keep our current level of activity strong, then we are probably going to be valued as one of SE's more worthwhile sites to keep (but we do have a disadvantage that we're the newest site, so if they do need to cut costs for some economic reasons, deleting our site might be seen as having less impact than deleting a much less activate site that has several years of Q/A posted in the past, so our requirements for activity level might have to be slightly higher than the average for an SE site).