...Requiring a paid subscription to the .net site will greatly reduce the traffic...
This is probably true.
...It might be a mistake.
This might not be true.
Putting any and all issues aside and looking at it objectively, to single-handedly run a large, active forum is an incredible
amount of work. Unless you are doing it as a labor of love you have a right to expect to be compensated for that work, especially if you are a working man.
If the financial return is not there to make the effort worth your while, then perhaps the best thing to do is to set it up as a subscription-based service and let it run while you pursue other things that will pay the bills. If it works, great, if it doesn't then you re-evaluate when the domain and server renewal bills come due.
Would it be a loss to the community if it goes down? Yes, most assuredly. Hopefully, if it comes to that perhaps a way will be found to preserve the history that is there. KLRWorld was once a huge resource, but all was lost in a server crash. It never came back, really, and is now down for good. It was an unrecoverable loss. Quite unfortunate.
Some decisions are hard and gut-wrenching to have to make, but business is business.