Straps Other answers have touched upon recommendations I'd do myself: put valuables in in your carry-ons and be prepared to not get your checked-in luggage (even though it is an extremely low probability). Having colored strings or even straps that completely surround the luggage could help. You could even write on or print on a nylon strap your name or some other blatantly obvious identifier.
Insurance Another option that doesn't answer your question directly but may assuage your fear is insurance. I've bought travel insurance in a couple of critical trips that I've taken throughout my life. One time my luggage didn't arrive on time; it was sent off to the wrong place in the world and it took a couple of days to come to me. By that time I would've needed toiletries and clothes to clean myself and —you know— function socially. Luckily, my insurance had foreseen this very scenario, and it basically covered all the expenses related to toiletries and clothes until my luggage arrived (I paid in full and was refunded a couple of months later). While my bag eventually did arrive, if it wouldn't have, I would've been given a compensation from my insurance. The airline didn't cover anything other than the delivery of the bag to my doorstep (which was great).
Bag management Another consideration to avoid robbery is to not leave your most valuable objects alone if you go to the bathroom. Or at least have a plan. I feel a bit ambivalent about bringing stuff to the bathroom, because I don't want to bring a whole backpack with my laptop and whatever into the airplane bathroom. I feel weird about it; I don't want to make other passengers nervous, if that makes sense (this may be a 'me' thing; I wonder what others on this site think).
So what I've come to do is to have multiple 'mini bags'. I have a hidden ultra-thin fanny pack that is hidden underneath my clothes, in which I store some money, my passports, and a boarding pass (although these last ones have been replaced by digital phone-based passes in the last few trips I've taken...). This fanny pack I take with me everywhere when flying. The only moment I get separated from it is during security checks. Other than that, always on me.
I also have a toiletries bag, which is just a big zip-loc with a small toothbrush, a small toothpase tube, a small deodorant bar, a small soap-something to shower without water (just in case), some wet-wipes, etc.. This bag exists in case I have an absurdly long flight or layover, or in case my luggage never makes it home (insurance notwithstanding).
Finally, I have a bag inside of my backpack. It's a bag made only of cloth, so that it can fold and not take space. I usually use it to leave my heavy backpack stationed with a friend (by which I mean a friend I'm traveling with, someone I trust—not someone I just met), while I wander around the airport in search for food or a bathroom. But I could put stuff in it and take it to the airplane bathroom with me, leaving my backpack under the seat in front of me in the meantime.
However, what I do when I go to the bathroom (and this is the "plan" that I mentioned earlier), is I simply check, once I'm back, that my computer, my camera, and my headphones are still there. I do this nonchalantly because I want to be polite to my neighbors. It helps that I actually use my computer while flying.
All of this narrows down the things that I need to worry about: not my passport nor money because they're on me, not my most basic toiletries because I have them with me, not my clothes because I'm (sometimes) insured, and probably not my laptop because I'd know quickly if they went missing and could immediately notify the flight attendant.
Hopefully this helps :)