I for one am of the mentality that gcses have got easier and easier. The change back to o- levels can only be a good thing.
And OP, I see your concerns entirely, however, you should not be revising just to pass the exam (although that is a bonus), you should be aiming to revise to store that memory away for a lifetime. We're all guilty of revising to pass an exam and then forgetting that information down the line 'as its not needed anymore to pass the exams ahead' and from what I gather, this is what they are aiming to prevent.
My only concern is that it has become widely accepted to choose many subjects for gcses, do they plan to keep this up and not raise the standard back to o-level requirements, or raise the standards to original quality and except that the students complete less subjects?