At the bottom of your link there, there is a phone number next to "IRS FBAR Hotline". That seems like the logical next step, as I am pretty sure that they won't just let it go. There are probably penalties that you have to pay for missing deadlines, but the longer you delay, the worse those will get. I'd call them ASAP.
[Disclaimer: I had no idea the sailing permit existed, and did not obtain one before leaving the USA]
It appears to me that IRS form 2063 does not stop you being a US person, liable for tax on your worldwide income and required to file an FBAR. It simply confirms that you have no current tax liability and are permitted to leave the USA.