Abbreviating guard...else with new syntax is a commonly rejected change. This particular suggestion hasn’t been listed in the document on such changes, but it would fall under the same umbrella as the others, I would think.
[EDIT] Note that the above linked thread is not an accepted direction for the language, it’s just a discussion.
Not sure I would want to be able to avoid guard statements where I’d otherwise be returning or continuing but the idea of throwing if nil coalescing fails is appealing to me.