Yes, skipping & entering your own code expression instead is akin to modifying the line statement.

I was also wondering about issues like breaking scope, etc. Here's a made-up example:

1:     while (<STDIN>) {
2:         push(@F, $_);
3==>       shift(@F) if $. > 10;
4      }
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I wish to replace line 3 with

    shift(@F) if $. > 10; }{ print @F;
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instead. This modification still results in valid code.

How far can we push this?