What happens to this checklist after launch?
From November 19, this page turns into the 100% completion tracker: missions, collectibles and activities, added as they are verified in the game. Nothing is listed before it has been found in the game.
How is my progress saved?
In your browser, on this device. There is no account and nothing is sent to a server. Clearing your browser data resets the list.
Sources : Rockstar Newswire.