What’s the cost? I think I’d disagree with just about every one of your items on that bulleted list — sure, none of them are huge costs, but they are definitely costs none-the-less.
The biggest cost, though? Developer time. Not only would this cost the time to implement it in base Julia itself, but it’d also require every single Julia grammar file to be updated for proper highlighting and indentation. And then there’d be the “forever” cost of folks who believe that this is the “better” way of spelling end slowly converting ends to endifs, endwhiles, and endbegins because “it’s safer” throughout the ecosystem.
Plus that last one, endbegin would just be bizarre.