You are not completely stuck if you can not upgrade to 10.3.4 before November 3rd. However, you must back up and restore to a computer if you want to switch to the newer software. Other devices like the fourth generation iPad are also affected, but are only expected to lose GPS functionality.
There will not be too many people affected. Apple states that since October 15, 9 percent of all iOS device users run software prior to iOS 12, and many of them use newer hardware (the percentage drops to 7 percent if you limit the data to devices that are four years or older ). , Yet, a company does not often have to ask people to update a device seven years after launch.