IssueTracker

If it were not for NFC unlock I would not use any kind of display lock at all.
Face unlock does not work properly, as well as trusted places.
Bluetooth would not make any sense, since I would have to unlock my phone to switch on bluetooth to have my phone unlocked by bluetooth (wtf ?).
On body detection is useless, too: whenever I carry my phone around in my pocket with the screen unlocked, all kinds of strange things happen when the screen gets activated by some app or another.
As for fingerprint, my phone does not have one. Even if my next phone had a fingerprint reader, it would be of no use when located in the back and the phone is sitting in any kind of holder or cradle.

We have passed this to the development team and will update this issue with more information as it becomes available.

@3 Please do consider re-adding this feature.
There are actually people who think it's an awesome thing to have. Even medical cases, such as this one:
https://issuetracker.google.com/issues/65425413#comment37

Bring back NFC unlock. Or add NFC U2F unlock with something like Yubikey.

Another thing I would like to see is custom Smart Unlock providers. This way a company like Yubikey could add support for NFC U2F dongles.

It was really useful to me, I had a nfc tag near my mouse pad. It was safer and much more precise compared to gps location!

I have found a workaround, though it requires root and manually editing a preferences file.
Details on pastebin: https://pastebin.com/2RSZzERg

Instructions found within comment #8 worked well for me to re-enable NFC Smart Unlock, hope it stays that way.  This is definitely something Google should bring back anyways as it's a fast and more secure way to unlock the phone that enough people still use plus the adoption of NFC based triggers will only grow IMO over time.

This is an absolutely necessary feature for me to unlock my phone by rings inside gloves when I have to wear a hat scarf gloves and sunglasses on cold sunny days, and I don't want to give pickpockets access to my phone through on-body detection

Adding myself to the people who used this feature regularly, and miss it now. :(

Now regretting my choice to not "share my usage anonymously with Google".

Please bring this feature back. I do fabrication work and my fingerprints are seldom I'm a readable condition.

Bring back this feature, please.  It was a brilliant idea and deserves further development.

Why "won't fix" ? It's so easy to bring it back...

Thank you for your feedback. We assure you that we are doing our best to address all issues reported. For now, we will be closing the issue as won't fix obsolete.

why?  if you are closing this as obsolete and won't fix, why not give an explanation as to why?

Please bring back this feature!

Bring it back please!

Please bring back NGF unlock! There are bracelets and rings that contain NFC tags and would be the easiest to use.

I use my smartphone as a navigator on my motorbike,
Unlocking with facial recognition is not possible by wearing the helmet, same with fingerprints since I use gloves.
With NFC positioned on the bike, as soon as I remove the smartphone it locks.
It would be very useful.

Dear Google Team,
Please bring this feature back.
It's useful and with proliferation and awareness of NFC these days (thanks to contactless payments and other applications), this could become a real benefit for users, and the low-usage of the past won't be an issue anymore.There's a huge number of use cases.

Please bring it back. Only reason I got NFC tags in the first place.