No I don't think sitting back and waiting is a good idea for MS, but I also don't think the SAD edition One S was a good idea either, not to mention the $250 price point on top of that. It's quite possible that no matter what MS does, it may not impact PS5 all that much either way if PS doesn't screw up. If MS hasn't learned by now, what makes you think they've got it figured out for next gen? Unless all these 'mistakes' are just bluffs, and costly one's at that.
Microsoft should have redesigned the online-only edition of the Xbox One S to truly differentiate the SKU. It could be a significantly smaller device for one... Then it might be a little more tenable.
I am seeing the discless Xbox One S as a "test" for next gen, if sales are healthy it might give Microsoft the excuse to release a next-gen console from day 0 at a lower price point without an optical disk drive, that way they aren't likely to tarnish their next-gen launch window if shit hits the proverbial fan.