So, just to be clear, the entire premise of your question happens to be wrong but that's not actually important? Because once it's established that English, Maths and Science are not the *only* subjects that are important, which is unarguable, then it follows that you don't need to replace them with anything, only ensure that other subjects are given attention and credit too. Similarly, the three subjects in question aren't being discredited, only the approach to teaching them and the emphasis placed on them to the expense of all else. I think you'd be hard-pressed to find a teacher that doesn't sympathise with that at least in part.
As it happens, when I clicked on the article, I only saw the Mail's headline, assumed it was accurate (because, of course, why would you print such an outrageously obvious error?) and was all prepared to get angry at Corbyn. Then I read the article and got angry at the Mail instead.