“Luke Skywalker has vanished” is not my favorite choice for a first line for two reasons.
The first is because it really doesn’t fit on one line without squishing the letters together. Take a look at the theatrical version and note how many lines, not just this one, are really crushed down to fit, and I’d prefer to avoid these issues if possible.
The second reason is that while it works for a returning audience, to someone who didn’t grow up with the OT and is completely new to the world, this line doesn’t communicate much of anything. You’d need a big paragraph explaining that he is a Jedi, why this is important, and what the term ‘Jedi’ actually means. Granted we try to do this anyway, but I think it’s more straightforward to lead with the state of the galaxy and then explain why it’s like this, which is what the ANH crawl did so well, and one reason why it didn’t bother to introduce terms like ‘Jedi’ until later in the film.