No one is going to be able to prove the CPU throttling was planned obsolecense. And what is planned obsolecense anyway? Apple doesn’t offer any guarantees on performance. When you buy an iPhone there’s nothing in the fine print that says you will get buttery smooth performance for x number of months/years after device purchase.
Such a lawsuit can go either way. I am by no means an expert in french law, but their definition is vague enough and cover things like e.g. programmed end of product life cycle, technical limitations and restraints of warranty. And don't forget that is a consumer law, not a specified technical documentation. As i said it is up to the court to decide if Apple did some malpractice. Until they find out, this is followed by some negative PR, which Apple imo deserves for their non-transparency.