We use 'likely' when we are not sure. If someone tells you , "Next year temperatures will go down" here we can not be sure about future because it's not definite that temperature will surely go down, it can even rise. So here you can answer as, "Yeah likely"
Whereas in the sentences where the event has already happened for example," These years prices have skyrocketed to unprecedented levels " here you can answer as " yeah definitely" because there is no doubt.
( Also there is another mistake in the first sentence of your question. It should be - I wonder if I could* respond* to someone's..." : )