If you have an Apple TV 4 and really looking to jailbreak the device now, this is your time. Currently, tvOS 10.2.2 is still being signed by Apple, this allows for downgrades to be possible even without SHSH Blobs.
NitoTV, the developer behind GreenG0blin, is working on getting a tvOS 10.2.2 jailbreak for the Apple TV 4. There are some things to keep in mind before you start downgrading or go out and buy a new Apple TV 4 in order to take advantage of this jailbreak though:
It is important to make sure you know what Apple TV 4 you have/are getting. If it's a new Apple TV 4 that comes in a white box, downgrading that Apple TV is risky as the remote that comes in the box will not connect with your Apple TV after you downgrade, because they are programmed to work on tvOS 11 and above. A way around this is to use an older controller to pair and go through the activation screen.
If you do not have an Apple TV 4 and are going to be buying one to take advantage of the jailbreak it is recommended you buy from a local buy and sell site and get the one that comes in the black box so you have full compatibility when you downgrade with your remote.
Keep in mind that you might not be able to use some apps such as Netflix if you didn't have them before updating to tvOS 11, so downgrade at your own risk.
You can find .IPSW files for downgrading the Apple TV 4 by visiting iPSW.me.