On the contrary, I implemented a substantial facsimile of it in a Lisp dialect yesterday; see my comment history.

  1> (load "template")
  nil
  2> (let ((field "name") (table "customers"))
       (te `SELECT @field FROM @table`))
  #S(template merge #<interpreted fun: lambda (#:self-0073)> strings #("SELECT " " FROM ")
              vals #("name" "customers"))
  3> *2.(merge)
  "SELECT name FROM customers"
  4> [*2.vals 0]
  "name"
  5> (set [*2.vals 0] "id")
  "id"
  6> *2.(merge)
  "SELECT id FROM customers"
  7> (upd *2.vals (map upcase-str))
  #("ID" "CUSTOMERS")
  8> *2.(merge)
  "SELECT ID FROM CUSTOMERS"

Unlike template strings, it was done in the language. There already are quasi-strings in the form of `...` syntax. We can quote that syntax (e.g. implicitly as a macro argument) and then pull apart its pieces to construct an object. It should work even in a years-out-of-date installation of the language. No new tooling is required; no changes to syntax highlighting in the editor, nothing.

It's a parlor trick that doesn't have any uses. The structured log messages use case is the most promising, because it has a consumer which actually wants the interpolated pieces that it would otherwise have to hackily parse out.

I predict that Python will eventually get dedicated HTML syntax: perhaps something that uses indentation to indicate element nesting. Let's "vibe pseudocode" a sketch:

   html:
     div (class='main' id='1'):
       p:
         "paragraph text"

or whatever.