Things that seem to be used less and less
- clothing irons
- wallets
- postcards
- handkerchiefs (I am not sure where you would even buy one)
- huge department stores
- multiplex movie theatres
- fancy dinner services and tea sets (my mother and grandmother adored theirs!)
- wallets
- regular milk (at some places in Stockholm you can only choose between oat milk and lactose-free milk)
- landlines
- business suits, particularly for women
- high heels during the day
- handwritten letters and invitations
- Physical Christmas cards
- keys
- cash
- postage stamps
- banks
- automatic teller machines
- post offices
- address books
and I don’t think there are such things as public phones anymore.

You mentioned wallets, however, I have seen lots of RFID wallets being sold here in the North East of England. There are also some public phones left but since the advent of the mobile/cell phone they are becoming as rare as dragons teeth.
Cheque books…
Germany is lagging behind in terms of technology so many of these things are still available. Using your debit card to pay has only become normal during corona times. Fortunately, we can still continue to use this system… I like handkerchiefs and they were hard to find (Amazon!). So during corona, I got into sewing and I bought some fabric and made my own. I suffer from allergies all year round so it helps me save plenty of money that way!… But during colds, I go back to paper tissues. In 10 or 20 years, more and more things are going to become obsolete…