I'm an iOS developer working for a company and in the next days we'll be publishing our customer .ipa compilation onto the app store.
The thing is we're perfectly aware of the 1st of April restrictions about "how to publish new apps", that is, we already know we need to use XCode 9 to add proper iPhone X screen layout support.
Anyway, our intention is releasing our app AS OF TODAY (20-Mar-2018), before the 1st of April deadline, with not perfect iPhoneX support yet. In fact, the .ipa file has been already uploaded weeks ago, and considered ready to be published by Apple. So far so good.
Now here comes our doubt: What would it happen if we keep the "approved status and ready to be published" of the .ipa file we sent some days ago, and perform the actual publish action under iTunes connect after the 1st of April? Would Apple refuse our (otherwise) already accepted .ipa file, which is now "in the oven" ready to be published?
After reading the new conditions about uploading .ipa files after 1st of April (with Xcode 9), we have no idea if the already uploaded .ipa file would make its way to the app store, or would be banned.
We sent our query to Apple.
Apple told us this: once the app reaches the "the only thing needed to publish your app is just pressing the 'publish' button inside your itunes connect", the app will get published, no matter what.
In case legal/technical conditions are known to change, if they apply after the app has been approved by Apple review team (as it will happen on 1st April 2018), the "invalid app" publishing action will be valid anyway.
In case other developing teams have this doubt, here you have Apple's answer to our query.