iPhone SE: forgotten passcode
Your question is old but still relevant. Sorry I didn't see it soon enough.

This is an important feature in iOS and has caused a tremendous stir among privacy advocates and law enforcement. Just do a search for "graykey device"

For all intents and purposes your iPhone is locked and will stay that way. Depending on the iOS version you have installed it may or may not be able to be "hacked" using a zero day exploit. This isn't realistic to the 99.999% of us out there who have forgotten some old pin lock.

You can use your iCloud account associated with the device, and IF you can see it with "find my iPhone/ iPad" you can initiate an erase command.

If you have synced with iTunes at anytime in the device's history, you can put it into DFU mode and restore that way.

The data is gone forever either way

I'm sorry but I see this occasionally, especially with senior citizens who walked out of the cell phone store with a shiny new iPhone, and haven't kept up their backups, never synced to a computer, and forgotten their Email account, email account password, itunes account, icloud account and the email account it's associated with... they lose all of those grandkid pics and videos.

It's the sad price honest people pay for security and privacy