Just to prove to the OP that I did read their proposal: The concept is that FD charge a subscription so those that want to play in groups have a more stable connection. Did I get it right and pass the test
Have you looked at who your intended market is? Well it wouldn't be anyone who plays primarily in Solo because they are already happy by themselves and will never see another player. So they are happy with the current system. Next is PG's - I suspect a small quantity might want a better connection but again, I suspect the vast majority probably don't interact with other players anyway. That leaves Open. But how many of those are like me, play 90% of my time in open but have never, and will never, wing up or interact with another player. I play Open because well it 'feels right', no one can accuse me of hiding (lol) and I do like the added perceived danger of Open. So again, your target market is only those that either PvP or find the game is more enjoyable playing with friends (more often than not to PvP as a Wing).
My estimations - you would be catering to less than 10% of the current player base and probably 50% of those would maybe take up the offer. The numbers just aren't there. Even for something momentous like DW2. Yes having a stable MP platform would be have been nice at the launch but after that when everyone headed out - they might as well be saving their hard earned by reverting back to Solo or PG.
Now look at the mechanics of your concept. It would be a very large undertaking by FD. Not only rewrite the code for the new system but maintaining it. Every patch would have to be run against both networking systems, and since FD seems to have trouble accomplishing that with one network, one can imagine the problems when they have to do their 'Q&A' on two different systems.
Finally look at the game itself. ED is one of those games nearly everyone takes a break from. They might stop playing for a week, a month or even longer because they know that when that itch returns they can just dust of the HOTAS and jump straight back in with no financial loss. But that can't happen with a subscription game, if you do decide to take a break the first thing you do is cancel your subscription. Then when the itch returns you have to make that decision: do you just play normal ED or start paying extra again?
TL; DR version: I respectfully say No to your proposal.