Using alignment as training wheels to help someone play a persona different than them makes sense, but it is very simplistic and like many crutches can often be a barrier to good roleplay. Alignment has an axis of three discrete values for Lawful/Neutral/Chaotic, when these are really continuous variables and often issue dependent for a character. I might be very law-abiding about certain rules, e.g. practice swordsmanship every day, never attack an unarmed man, obey all orders, but then less so about being loyal to my spouse, honest in my business dealings, etc.
This is why I expect that Ideals, Bonds, and Flaws will end up having much more of an impact on the creation and playing of personas than alignment will (even if it is reintroduced to the game by a specific DM.) A moral compass gives hints about how you'd behave in generalities... but having specific ideals you follow, people or things you are emotionally connected and bonded to, and discrete character failings all are easier to understand in the micro of playing.
Your alignment might be Chaotic... but if you couple that with a Flaw of 'Rash'... that's much easier to understand and play. Your alignment might be Neutral... but if your Ideal is 'I treat everyone I know and meet like a negotiating partner regardless of who or what they are', that's much easier to understand and play. Those kinds of specific things are comprehensible and can easily point you in the direction you want in most situations.