The Supreme Court had already ruled that the President is the sole authority on classification/reclassification/declassification. Obama's executive order was just a guide for how he wanted that authority exercised during his administration.
Again, the President's power of classification/reclassification/declassification comes from the U.S. Constitution as ruled by the USSC. No Obama EO can limit his successor's constitutional powers, any more than Trump could have issued an EO stating that Biden the president is not the Commander in Chief and have it be binding on future presidents.
Even if you were right and that EO was binding during the Trump administration, line 5, which I bolded and colored red, certainly would include the President.