I think the best solution is to enforce 4 digit year on the input and in dates coming into the system.

Sure somebody could not have been born yet in 2029. And if you know the column name is known to be of a specific date type (e.g. birthdate, employmentdate, deathdate, order date) then you can throw logic at it. But then you have further complications with maintaining that code and ensuring somebody doesn't change something on you.