I agree with you, maybe they need a better coach. I think Zidane and Conte is better choice. Moreover, I have not heard they have joined the club. The reason is that they are more experienced, Zidane and Madrid have won the UCL Conte won Serie A and joined the UCL with Inter.
Of course Newcastle's target will be more than winning the Premier League, I think they will have a target of getting into the UEFA League or UCL. All that is not owned by the current Newcatle coach.