Prosites for non-multisites

I have quite a few blogs on a multisite pro-sites configuration which is great! But for some users/clients they need more plugins, customizations, and space than I can allow inside the multisite. I would like to suggest a new plugin.

Prosites External Plugin - Thoughts (needs a better name)

Installation:
- I would install the main plugin on my site
- I would install a sub-plugin on the client site
- The two plugins would connect somehow - Somewhat like ManageWP but with recurring payments

Main Site Plugin:
Ideally the main site would have a dashboard of everything going on in this plugin. Could include payment details, site name, and if any plugins need to be updated.

- Ability to rename the plugin from pro-sites to anything
- Shows if client has paid
- Shows if plugins need updating on client sites
- Ability to setup either PayPal Pro or Stripe gateway
- Ability to accept recurring payments
- Allows for manually extending status
- Account history

If a client didn't pay the plugin could turn off all access in the WordPress dashboard except for the payment screen. On the front end it could show a down for maintenance screen like

https://premium.wpmudev.org/blog/a-quick-and-easy-way-to-put-your-wordpress-site-into-maintenance-mode/

This would be a dream come true.
Does anyone else have a need for this?

I added this to the voting pool as well here http://wpmudev.uservoice.com/forums/148158-wpmu-dev-new-development-requests/suggestions/2613527-prosites-for-non-multisites vote for it if it will help you