I love the idea of reviving the competition in one form or another and there are some interesting ideas in this thread.
For me I feel themeless is a bad way to go. I used the themes as a way to encourage me to try new styles/take photos of things I wouldn't usually do. Yes I struggled with some months but that was part of the fun for me. If it went themeless I think I'd lose the motivation to enter without a specific goal in mind.
My Idea: What if the themes were simply photography techniques rather than subjects? So February's competition could be Rule of Thirds, March could be Bokeh etc. It helps the beginners learn good technique and possibly even remind the more seasoned among us that don't necessarily use all the techniques very often? It also leaves the subject relatively open to be anything you want (i.e. if you want to enter a wedding photo every month that complies with that months specified technique, then go for it). They could also be specified in advance for the year if need be once everyone agreed on the techniques.
Monthly still feels fine with me, any less and I think people may lose interest while waiting between themes. Likewise the scoring should be done a bit quicker than the last competition was for the same reason.
As for voting/scoring....Peer marking by those that have entered seems like a good idea, whether its via email or a thread
Just my 2p