I own a few smart TVs. Not all remain so. Some manufacturers stop supporting them after a while. They stop receiving updates or the apps stop working. Eventually nothing works and they become a monitor, a screen.
You end up sourcing another device to re-enable the feeds you subscribe to. A USB / HDMI stick, a games console, or a set-top box of some kind. The smartness moving outside of the screen hardware into an externally connected device.
Some retailers offer up to 5-years cover on the hardware, but not for the software. That could end in a year or maybe two if you are lucky.
Your smart TVs are basically PCs with no upgrade potential. At some point the manufacturer will cease all support and you can’t upgrade it. Better to buy a large computer monitor and have the smart part in something external that can be upgraded or is cheaper to replace.