If I've understood what you're asking correctly, one would assume that provided the functionality of statement 3 remains unchanged but the code was just refactored. The test wont fail but it wont necessarily pass as it hasn't covered statement 3.
If you want it to pass for all then you will need to adjust the code accordingly (if required) to match the ...
Depends with what you mean by "not hit by this test case".
If you mean traditional code coverage, yes, it is possible.
Metaprogramming allows you to change the structure of code at compile and run-time in ways that may create dependencies in good* unit checks.
Aspect-Oriented Programming changes behavior in a similar fashion.
Also, if you have checks ...