Listen okay, Apple won't be bringing out a 5.5" iPhone - to think they will is plain daydreaming and self-delusion.
No. Way.
Let the Android mfrs make all the skateboards they want - if you think Apple would do this, you don't know Apple very well; if 5.5-6" is too big to be held comfortably on other brands, what makes you think Apple's 5.5" is suddenly, magically going to be easy to hold? They're the best, but they cannot change physics.
Wake up folks, snap out of it - Apple aren't looking at what we want, they design what THEY want to design, and they'll do it how they want, and take as long as they take - if it seems idiotic and unwieldy to have a 5.5" any-brand phone, then don't you think Apple know that? Designers don't live in a vacuum - they're not morons - hardware designers do repeated ergonomics tests, prototype iterations and refinements, usability studies and on and on... Apple HAVE bigger iPhones to hold and to actually feel and try - we don't - they KNOW what is coming, what has worked best and what is fit in form and function, and all WE have to go on is some dreamed-up JPEG that someone "leaked", some render based on (supposed) "leaked blueprints" - we have NOTHING physical to base assumptions on apart from the models released to date, and other mfrs models... but we DO NOT have Apple's prototypes, insight and PHYSICAL HANDS-ON TIME WITH *REAL*, WORKING PROTOTYPES.
It's all just guess work, and most of it seriously underestimates Apple's proven capabilities in designing things that you, repeatedly, didn't see coming, year on year.