Wait to Future Proof Your Smart TV
If you are thinking of buying a 4K TV during Black Friday or in the next year, you should wait for the 2017 Apple TV release date to buy a new Apple TV.
This will allow you to future proof your streaming solution, and still enjoy it on your current TV. A 4K Apple TV will still work on a standard HDTV and when you are ready to upgrade you can plug it in using the same HDMI cable to a 4K TV and get a better picture.
Even if you think you will be buying a new 4K TV in 2018 for the Super Bowl, it's worth waiting for the new Apple TV to buy one. The only real reason not to wait is if you don't plan to buy a 4K TV in the next 1-2 years.