A smart TV can be a dumb TV if you never connect it to the internet and just plug in whatever you want to it via HDMI. I have a 'smart' TV myself and the only buttons I use on the remote are power and input select. It's never seen the internet since I've had it.

I'm sure it's only a matter of time before these TVs require 'activation' and frequent 'reactivation' before you can use them though. Alternatively they may perhaps start connecting to cellular networks, which would be a lot harder to evade.