Some customers may be interested at many/high prices - proofofexistence.com costs $2 now!?  Yet i could post a hash in bitcoin transaction myself and waiting for a low fee, no?  - which bloats bitcoin blockchain but for the time being is better/easier/not relying on more -  Yet keeping paying customers ultimately depends on Factoms business relationships,
- if it gets too expensive customers/competitiors could start running another Factom network/chain being opensource.