Simply:
Add a "Final Fantasy XI" Crysta option for $11.95
This is not as convenient as the way it has been, and we still have to pay in $5, $10, etc increments for characters- but at least it will even out nicely from month to month. I can not think of any reason why this can't be done, and if this option is not added I would like to know why.
You could even get fancy with it and create a Warrior's Crysta($11.95) to indicate its purpose.
Doing this would, without a doubt, increase your sell of Crysta. The little chunks of leftovers that your FFXI customers are currently being forced to add-on would come nowhere near the additional customers that would otherwise not be buying that $11.95 worth of Crysta every single month given this option.
If one account means anything to you, personally this option (or another one that is trustworthy and void of additional fees) will likely be the difference between $0 a month from me and my continued subscription. For every person who gets fed up with the options we've been given, you need about five more players buying Crysta with that additional cost (assuming 1-2 characters) just to offset your loss. If that was my money on the line, I would definitely not be willing to take that gamble given the current reaction.
Finally, SE has had problems with urgency in the past and I hope the people responsible for decisions like this realize the urgency of the situation we're in now. If your lack of a response disrupts someone's habitual subscription payments, you can not expect them to come back a month or two later after you've provided the alternatives that they were asking for before they gave up and left.
Two facts:
1) This situation, left alone until the deadline, will cost you subscriptions- probably a rather significant amount more of them than you were expecting.
2) A large margin of those lost subscriptions will not come back after they're gone, no matter what. Not out of anger or principle, but simply because habits don't always look back.
Stop being so hands-off with this issue and fix it before it's too late.