OP, here's what you do: buy an iPad or Mac or whatever at the nearest Apple Store. They have a 14-day no-questions-asked return policy. If, two weeks later, you decide you done fucked up, just return it. Personally, I did what you're doing now between 2013 (when I got my first Mac) and 2015 (when I got my iPad/iPhone/Watch). I don't regret it at all.
My one iPhone-specific piece of advice for you is this: AVOID the iPhone 6. It's the worst iPhone that's still supported. That goes double for the 6 Plus.
Honestly, at this point, being "locked in" to the Apple ecosystem is like being confined on Earth by a lack of space travel. Sure, you're technically constrained, but there's still a shitload of things to do, and you'll find you can do almost anything you would want to do anyway. Just about the one thing you can't do reasonably well on iOS at this point is programming.
Android user from 2011-2015 here. It's only superior if your time is worthless.
Sketchy as fuck. Don't rely on these shitty MVNOs' unlock policies if you don't have to.
Honestly, we've heard all of this shit before. "Just wait until Google rolls out _____! It'll blow out all the competition!" And it never happens. The carriers, the OEMs, or Google themselves inevitably end up fucking it up somehow.
Honestly, if you're thinking about it, you probably won't regret it. I know I don't.
Seconding this. The iPad will surprise you, it's the world's best tablet.
Tell that to the multitude of people I've met whose iPad is their only computer. They seem to be getting along pretty well, especially at the $329 price point where iPads start now.
Killed Flash. Man, that was easy.