You can USB or network boot a Pi. Also in my experience over 9 years: just don't use Sandisk cards and you're fine. Samsung (Pro|Evo) branded cards have worked for me.
Network boot adds even more points of failure. USB boot is very attractive, but also very new. I’ll play around with it once it’s out of beta and the setup procedure is established.
I use Samsung Evo cards and haven’t had an issue with them either. My problem is one of confidence. I have no data to suggest that these cards won’t just hard fail at some point in the next five years. Simply doing better than their competitors in the micro SD card space is not good enough.
All of the dead cards, if I open my drawer where I store them marked with a black cross-mark, are samsung evo cards. All my Sandisk Ultras (the real ones verified on Sandisk's chinese website) are still running fine after ~3-4 years of usage.
Anyway, Samsung Evos didn't hard fail for me. They just stopped executing writes (without reporting any errors). So your system seems to work (for a while), but after reboot it's back to where it was previously. It's a pretty stupid way to handle end-of-life condition for the card. I wish samsung decided to report write failures instead of simply ignoring the writes and reporting success.
Same, have some units that have been running nonstop for the past 5 years without having to touch them at all, using Evo cards. Also, I don’t think I mounted var/logs as a tmpfs.