At this point I don’t think this is just because of iMessage. I think that even if Apple puts iMessage on Android, most won’t switch simply because it’s not an iPhone. iMessage is definitely a big part of it, but iPhone is a lot more than just iMessage. The iOS experience is unmatched in my opinion. Android comes close, and it definitely is more open with sideloading and multitasking, but that stuff is niche. I don’t think there’s really anything that differentiates Android from iOS that matters to the majority of people. It’s just less smooth, less cohesive, you have to wait for updates unless you have a pixel (or you might have a phone that will not get updated ever), the same apps aren’t as good as they are on iOS and they often don’t get features at the same time as iOS, the list goes on. Sure there are phones that have more hardware features but again those clearly don’t matter to the majority of people either since everyone keeps getting iPhones. I don’t like this trend.