New name: I think the Blocktopia name should stay, but add another word after it that relates to the direction that the community wants to be rebranded as? Personally, I think Blocktopia Network or Blocktopia Gaming would be simple without overthinking it.
New forum layout: How old is that background image for the forums? Maybe with the new forums, you can get a community event going on where people would be able to submit background images (logos, etc.) for the forums. There are a handful of players on here that do art/creative things so it would be nice to see their work on the site if this is really a community driven overhaul.
Removal of some Minecraft Servers: This part shouldn't be taken so lightly. You have great developers who took their time and effort to create their respective servers and if their server is shutdown, then you'll essentially lose them unless they agree to it and help whichever servers are kept. Then there are the players who come on from time to time that only play on one or two specific servers, if they don't have those servers to go to anymore, then they'll eventually have to find another community to go to if they feel like it. Overall, the remaining servers that the community/admins choose to keep should be solid servers that don't have any hiccups/errors but can be fixed/updated with new content from time to time to keep the players involved and essentially happy.
Streamlining staff structure: The current ranks are: Asshat, Admin, Director, Developer, Controller, Operator, and Trusted. I don't know about this change, but maybe Controller and Trusted could be altered/removed.
Servers/Support for popular games: From what I've seen, there has been those random events such as the Werewolf/Vampire(?), Trouble in Terrorist Town, Pixelmon, and probably a couple more unrelated to Minecraft -- I can't think of them off the top of my head. But the idea here is that maybe these servers should come on every other month. Lets say, TTT could be up for one month then Pixelmon the next month. Or have two different servers come up at the same month -- Like TTT/Pixelmon for January, then Werewolf/TeamFortress for February, then LoL/WoW for March, etc. (I don't know how these games/servers will work, but that's the idea.) Also, maybe put a Plug.dj forum up and promote it as well?
Community Events: n/a
Cleanup of ranks: n/a
As far as the Cons/Threats of the proposed changes go: Of course it might be a huge project and the risk of doing this may be better than what Blocktopia's current state is at. But who is going to be working on this and implementing the ideas? A select few? There really has to be people that will invest part of their time to help out and refresh the community within a certain time constraint so that things could be done instead of having the community wait for, who knows? how long this update could take.