Andrea Allred hits identity integer absolute zero:
Recently we had a system go down because we ran out of integers. (Mental note to create an alert when we are getting near to running out of integers.) If we upped the column to a bigint we were going to have to drop all the indexes. This server doesn’t have the capacity needed to do an operation of that size and it was estimated that it would be down for 8 hours while we dropped indexes, upped the column type and added back the indexes. This was way too long as it was early in the work day (had it been evening, it would have been fine).
There was also a concern about how many stored procedures were expecting an int but would need to be modified to a bigint, along with any code. That was a big undertaking and we were in an emergency down.
This reseeding typically works well, though it’s important to know if the code will fail upon getting negative numbers.