Of all the moats Apple has, iMessage's "blue bubble" is by far the most arbitrary.100% I have been an iPhone user since 2009, but for me the most likely reason to go to the competition is not if it gets iMessage (I don't live in the US). The most likely reason is that Apple has become utterly boring when it comes to innovation. I recently purchased an iPhone 15, coming from the iPhone 13, I can honestly not say what has changed or improved besides the camera, the underused dynamic island, and USB-C [1]. And USB-C is nice, but pretty much a letdown because they capped it to USB 2 for market segmentation and it still has excruciatingly slow charging. At least on the Android side, for better or worse, interesting stuff is happening: from Fairphone's phone that is repairable with a single screwdriver, foldables (finally a phone that is small and big), Samsung S-Pen, to Nothing's slightly whimsical back LEDs. Also, pretty much every phone above 300 Euro has a good OLED screen with 120Hz, whereas I am still looking at 60Hz (because segmentation).
At any rate, Tim Cook will fight this nail and tooth. By now it's very clear that he has a blind spot where he thinks Apple is entitled to some things and is not sensitive to different viewpoints in other cultures/legislations. He thought Apple is entitled to a 30% cut. But he pushed it so far that the EU will regulate them. Now they have to offer side-loading and open the iPhone to alternative app stores. This will lead to segmentation of the platform, because some apps will only be available in app stores with better terms for the developer.
Ideally Apple would stop Beeper in its tracks by releasing an Android client themselves, because then they could dictate their own terms (orange bubbles, feature segmentation, etc.). Now they open up themselves to the risk that regulators in some regions will require opening up iMessage.
[1] Of course, the spec sheet contains more improvements, like a better SoC, but it is barely noticable.