> ... replacing letters with email ...

Some true, but not totally. The role of email has many differences from old-age letters. And letters are not only replaced with email, but also more modern communication manners. And the more modern communication manners not only replace letters, but telephone etc.

And the letter case is specified case. There are many old-age things which are not replaced totally.

The same is for AI. It will replace something, but not all.