Messages

-Allowing the existing customers to stay on the system as long as they desire, but this will require us to finally get rid of all of the extra Plesk servers to bring our costs down.

I Agree with this option. The service and offerings has gotten better over the years and I personally would like it to stay.

Would a "referral" or "authentication" system work for new sign-ups?
So, this way current customers could invite "trusted" friends that may want to sign-up (2 per year), hopefully that curb fraudulent accounts

I renewed and will continue to do so, but I understand if you need to discontinue due to increased costs.