I also think Markdown is the choice of the future, but ATM, it's too limited to use in a forum. For example, what if I wanted to add a spoiler to the post, or a dice roller, or float an element, etc. Currently, there's just no easy way to add these things to markdown is there?

As far as BBC editor's go, I prefer the Sam Clarke editor: http://www.sceditor.com/

Please, no bootstrap editors.

I would like to see the ability to purchase a subscription, that will put a user into a group with extensive permissions. Also, when the subscription expires or is not renewed, remove that user from the specified group.

I recommend using Paypal(most common), 2Checkout(better system), and Coinbase(for accepting bitcoin). The reason I recommend coinbase, because they are the only ones with extensive API, that allows you to sell or trade your bitcoin for local currency.