Protect an entire blog in a multisite setup?

I am running a multisite setup.

What I am trying to accomplish

Each website on the network will require a unique membership level. This means that instead of protecting individual content sections on a single blog, I want to block access to an entire blog to all but paid members.

Think of it this way:

1. I sell themes and plugins on my ‘root’ website on the multisite install.

2. Each theme or plugin has its own dedicated support site (sub-domain + domain mapping)

3. The user pays for a theme or plugin and their membership level changes to grant them access to the corresponding support website for that particular product.

4. If a user visits a support site and does not have the proper permission levels to see the site, they are then redirected back to the purchase product page, or at the very least they see a page saying it is for members only.

Is this possible with membership yet?

*It seems to me that every single ‘members’ type of plugin on the market only seems to protect individual content sections and not entire sites without a ton of work involved. I know I requested this last year, but I was just checking back to see if this feature made it in or not.