As long as your TV has more than one HDMI port, which any reasonably modern TV should, then yes. You just have to switch HDMI inputs depending on which device you are currently using. Newer TVs can potentially do this automatically based on which remote you are using if HDMI-CEC is enabled in the TV's options.
Edit: Mis-read the original question, and realize now this is asking about buying a TV with Roku or Amazon TV capability built in. As, answered above, that is no different than buying any set with built in "smart" features(which is most sets now), and the answer is yes, this is not a problem.