We've had similar discussions with customers in the past - we've found the vast majority (90%) are happy to pay monthly, and the remainder are very vocally against.
We are looking to accomodate both sides, and the current plan is to offer a subscription 'pause', where all of your existing data is stored for free, and you can unpause to edit/create new projects.
It's still being worked out, but hopefully this will be a happy medium ground in the future.