Obsolescent
/ˌɑːbsəˈlesnt/
Definition 1 of 1
Pro Tip 1/3Tech Evolution
Obsolescent is often used when discussing the natural aging of technology due to new inventions. 
VHS players have become obsolescent with the rise of streaming services.
Pro Tip 2/3Not Extinct
Obsolescent implies something is becoming obsolete, but it's still in use, unlike 'obsolete' which means it's no longer used. 
Fax machines are obsolescent, but some offices still use them.
Pro Tip 3/3Cultural Shifts
The term can describe ideas or practices that are going out of fashion due to changes in societal norms. 
Writing letters by hand is becoming an obsolescent practice.