Of course he will be a definite starter, Chelsea do not have any striker that is better than him, notwithstanding his age. Quite a lot of people think Ronaldo is slowing down, but i don't think he is, definitely he can't be as sharp as he was 10 years ago, but he is still a productive footballer that is far better in his position than many players younger than he is. Aubameyang can't compare to him in anyway, and Tuchel who was the main reason Aubameyang came to Chelsea is now gone, so tbh he looks lost already and that could be the reason for his poor start to life at Stamford Bridge, if i am to help Chelsea make decisions on who to sign, i will definitely get Ronaldo for one season at least, with a possibility of an extension, it is a smart deal imo.