Thumb drives are now called USB flash drives.
Other names for thumb drives are memory sticks and pen drives.
Thumb drives use flash memory for data storage and plug into the USB port of any computer.
USB sticks are not being phased out although due to the rise of cloud storage and other data storage options available the USB memory sticks are not as popular as the used to be.
Still though USB sticks or USB memory sticks are still very popular and popular enough that they are still being made and sold and it's unlikely that USB memory sticks are gonna be phased out anytime soon.
USB sticks are also good for boot drives as well and installing software along with backing up data and carrying that data with you.
Many people do still use USB flash drives as they are compact, portable and easy to store data on and take the data where you need too.
USB flash drives will likely be used for many years as they are very good and reliable for data storage although you should also store data on other drives as well including online for important data that you want to back up.
The lifespan of a USB memory stick is around 10 years.
However some USB memory sticks may last longer than 10 years and some USB memory sticks may last less time.
The actual lifespan of the USB memory stick also depends on the write cycles and erase cycles.
The more write cycles and erase cycles on the USB memory stick the shorter it's lifespan.
USB memory sticks can handle between 10,000 to 100,000 write and erase cycles depending on the USB memory stick.
The number of the write cycles on the USB memory stick also affects how likely the data on the USB memory stick is to deteriorate.
The cheaper models of USB memory sticks tend to have shorter lifespans and the more expensive USB memory sticks tend to last longer.
USB memory sticks or flash drives can also fail prematurely if they get abused or are exposed to any extreme temperatures or humidity.
The signs that your USB memory stick are failing are the files are unreadable or inaccessible, the available space on the USB memory stick is less than advertised, the computer doesn't recognize the USB memory stick and the read and write cycles of the USB memory stick are slower than normal.
To extend the lifespan of your USB memory stick you should eject the USB memory stick before removing it, keep it in a good safe place, avoid exposing the USB memory stick to any humidity or extreme temperatures and if possible use high quality USB memory sticks or flash drives which use Grade A memory.
After 10 years I would not rely too much on the USB memory stick for keeping the data safe.
Always backup your data on multiple drives and memory sticks to have copies in case the USB memory stick or one drive happens to fail.
I back my data up on multiple drives, online and offline and don't rely on just one memory stick or hard drive to store data.